Resin for toner and toner

ABSTRACT

A resin for toner containing a resin component having both a polyester unit produced by polycondensation of a polyhydric alcohol component and a polycarboxylic acid component, and an aryl group having a sulfonic ester group as a substituent; and a toner that contains the resin for toner.

This application is a continuation of International Application No.PCT/JP2006/322909, filed Nov. 10, 2006, which claims the benefit ofJapanese Patent Application No. 2005-327142, filed Nov. 11, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a resin for toner contained in a tonerused in an image forming method utilizing electrophotography orelectrostatic printing or toner jet image forming method. In particular,the present invention relates to a resin for toner contained in a tonerto be provided in a fixing method that involves fixing a toner imageformed by the toner on a print sheet such as a transfer material underheat and pressure. Further, the present invention relates to a tonerthat contains the resin for toner.

2. Related Background Art

Conventionally, the image forming process utilizing electrophotography,electrostatic printing and so on is constructed such that anelectrostatic latent image on a photosensitive drum is developed byelectrostatic force depending on a potential difference on thephotosensitive drum. In this case, toners are charged by frictionbetween toners or between a toner and a carrier, and further due tofriction with a control blade. Therefore, it is indispensable to controlthe chargeability of toner in addition to control of toner particlediameter and particle diameter distribution and so on.

To control the chargeability of the toner, the triboelectric property ofthe binder resin itself may be utilized. However, binder resins commonlyused for toners have low triboelectric properties so that it isdifficult to control the chargeability by the composition of the binderresin. Accordingly, generally, a charge control agent is added in orderto impart chargeability to the toner.

Conventionally, negatively chargeable charge control agents includemetal complex salts of monoazo dyes; nitrohumic acid and salts thereof;metal compounds, boron compounds, urea compounds and silicon compoundsof salicylic acid, alkylsalicylic acids, dialkylsalicylic acids,naphthoic acid, dicarboxylic acids and so on; calixarenes; sulfonatedcopper phthalocyanine pigments; chlorinated paraffins, and so on. Thosecharge control agents have complex structures and are variable in theirproperty and many of them have poor stability; in particular, most ofthem vary in chargeability depending on their environment such astemperature and humidity. Also, some of them are denatured due todecomposition or the like upon kneading with heating.

Further, the charge control agent to be added to the toners must bepresent on the surface of the toner in a certain amount to imparttriboelectric chargeability to the toner. For this reason, the frictionbetween the toners, collision of the toner with the carrier, friction ofthe toner with a conveyor sleeve, a roller, a control blade, aphotosensitive drum or the like makes the charge control agent to comeoff from the surface of the toner, which may cause contamination of thecarrier and so on, and contamination of a developing member, thephotosensitive drum and so on. In this case, an increasing printingnumber of sheets leads to a decreased chargeability and results inprogression of deterioration of peripheral members and causes problemssuch as a change in image density and a decrease in image quality.Therefore, a difficulty in coming off of the charge control agent fromthe toner must also be taken into consideration.

Further, to be applicable to full color toners, additives to the tonersare preferably colorless, and further, to be usable for polymerizationtoners, the additives preferably have no polymerization inhibitingproperty.

As described above, many properties are required for charge controlagents. Then, a charge control agent that can impart sufficient chargesto the toner stably for a long period of time is demanded.

Further, processes for fixing toner images that have been developedinclude a pressure heating process utilizing a heat roller (hereinafter,referred to as “heat roller fixing process”) and a heat fixing processthat involves fixing the toner images while contacting a sheet to befixed with a heating member through a fixing film (hereinafter, referredto as “film fixing process”).

In the case of heat roller fixing process and film fixing process, thesurface of the heat roller or fixing film is in pressure contact withthe toner image on a sheet to be fixed. Therefore, the thermalefficiency of fusing the toner image on the sheet is extremely high.This allows rapid and good fixation to be performed.

In recent years, electrophotographic apparatuses are required to havevarious properties such as high image quality, compact size and lightweight, high speed and high productivity, low energy consumption, highreliability, low cost, maintenance free property and so on. For thefixing process, development of a system and a material that can achievehigher speed, lower energy consumption, higher reliability is demanded.However, to solve those problems by the heat roller fixing process andfilm fixing process, it is indispensable to improve the fixingperformance of the toner to a greater extent and it is necessary toimprove low temperature fixing performance and also anti-offsetperformance.

Toners that contain wax having a high affinity with the binder resinexhibit good anti-offset performance and low temperature fixingperformance under specified fixing conditions (see, for example,Japanese Patent Application Laid-Open Nos. H08-050367 and 2001-318484).However, in those toners, wax becomes compatible with the binder resin,so that the glass transition temperature of the toner and the meltviscosity of the toner tend to be decreased. In this case, if a furtherimprovement of low temperature performance is attempted, chargeabilityin addition to storage stability and flowability tends to bedeteriorated; in particular, when continuous printing is performed, aremarkable decrease in image density or a faulty image tends to occur.For this reason, a toner that has an excellent chargeability while ithas an excellent low temperature fixing performance is demanded.

Incidentally, prevailing printer apparatuses include LED and laser beamprinters in recent markets and a higher resolution is required in thetechnical trend. Further, copying machines are also in progress toward ahigher function and hence toward digitalization. This direction oftechnology, which is mainly attained by a method of forming anelectrostatic latent image by means of laser, also aims at a higherresolution. In addition, the developing method is required to be able toprovide high precision images. As one means to meet the requirements,development of a toner with smaller particle size has been under way andtoners having small particle sizes within specified particle sizedistributions (see, for example, Japanese Patent Application Laid-OpenNo. H01-112253, Japanese Patent Application Laid-Open No. H01-191156,Japanese Patent Application Laid-Open No. H02-284156, Japanese PatentApplication Laid-Open No. H02-284158, Japanese Patent ApplicationLaid-Open No. H03-181952, and Japanese Patent Application Laid-Open No.H04-162048) have been proposed.

However, the smaller the particle size of the toner, the more importantit is to control the triboelectric charge of the toner. That is, in thecase of the toner having a small particle size, failure to impartuniform charge quantity to individual toner particles results in aremarkable decrease in image stability. The reason will be as follows.(1) A toner having a smaller particle size has a greater affixing power(mirror image force, van der Waals force, etc.) to the photosensitivemember, resulting in that the remaining toner after transfer tends toincrease. (2) A decrease in toner particle size is accompanied bydeterioration of flowability, so that the charge quantity of individualtoner particles tends to be non-uniform, thus causing fog or a decreasein transferability.

Under the circumstances, a study for improving the charge properties oftoner has been conducted intensively and in recent years, it has beenproposed to use a resin having a charge control function as a rawmaterial of toners because of consideration on environment, requirementfor more stable chargeability, production cost, and so on (see, forexample, Japanese Patent Publication No. H08-012467 and Japanese PatentNo. 2663016).

According to the literatures, toners having an improved chargeabilitycan be obtained. However, studies on the toners performed by theinventors of the present invention reveal that when the number ofprintouts becomes larger, toners of opposite polarity gradually increasein the developing device, which leads to a problem that so-calledreversal fog tends to occur. Further, there is room for the toners to beimproved for their low temperature fixability.

Further improved toners containing a copolymer of a sulfonic acidgroup-containing acrylamide and a vinyl monomer have been proposed (see,for example, Japanese Patent Application Laid-Open No. H11-184165,Japanese Patent Application Laid-Open No. H11-288129, and JapanesePatent Application Laid-Open No. 2000-056518). For the technologiesdisclosed in the literatures, however, there is room to be improved ofcharging performance (in particular, initial rise performance) whenprocess speed is increased by a contact single-component developmentsystem or the like.

Conventionally, several proposals have been also made on the improvementof chargeability of the resin having a charge control function (see, forexample, Japanese Patent Application Laid-Open No. H01-191156 andJapanese Patent Application Laid-Open No. HO-2284156). According to theliteratures, toners showing relatively good rise in chargeability andhaving good dispersibility of various additives in the binder resin canbe obtained. However, there is room for improvement of the stability ofcharge quantity before and after endurance running or under hightemperature and high humidity and transferability.

Further, proposals have been made to use polyester resins having asulfonic acid group as charge control resins (see, for example, JapanesePatent Application Laid-Open No. 2003-215853, Japanese Patent No.2972987, and Japanese Patent No. 3179663). However, there is room forimprovement of charging properties, and in particular, the stability ofcharge quantity under high temperature and high humidity conditions wasinsufficient.

SUMMARY OF THE INVENTION

Under the circumstances, the present invention has been made.

That is, it is an object of the present invention to provide a tonerhaving a good fixability and charging properties.

It is another object of the present invention to provide a toner thatcan provide stable images from an initial stage to after printing out alarge number of sheets.

As a result of extensive investigation, the inventors of the presentinvention have found that the charging performance of a toner can beimproved and a resin for toners having excellent fixability, developmentand transfer properties can be obtained by attaching an aryl grouphaving a sulfonic ester group as a substituent to a resin having apolyester unit. The present invention has been achieved based on thisfinding.

That is, the present invention relates to the following resin for toneror toner resin, and to the following toner.

(1) A resin for toner comprising a resin component having both apolyester unit produced by polycondensation of a polyhydric alcoholcomponent and a polycarboxylic acid component, and an aryl group havinga sulfonic ester group as a substituent.

(2) A toner comprising toner particles that contain at least a binderresin, a colorant, and the resin for toner.

Use of the resin for toner according to the present invention allows forproviding a toner that has a good low temperature fixability and astable triboelectric chargeability, excellent developability andtransferability, and is capable of providing a stable image for longperiod of time.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The most characteristic feature of the resin for toner according to thepresent invention is that it contains an aryl group having a sulfonicester group as a substituent. As compared with the resin having asulfonic acid group that has been conventionally proposed, a resinhaving a sulfonic ester group makes it possible to improve the chargingperformance. As a result, the toner that contains the resin hasexcellent rise properties of initial triboelectric charging. Althoughthe reason for this is not clear, it is presumed that a sulfonic estergroup has a stronger hydrophobicity as compared with a sulfonic acidgroup because the electron absorbing property thereof functions withoutinfluence of water molecules in the air. Further, a functional grouphaving a salt structure such as a sulfonic acid salt group is liable toinfluence of water molecules in the air in a high temperature and highhumidity environment, so that a decrease in electric resistance on thesurface of the toner tends to occur. Therefore, the sulfonic ester groupis superior in stability of charge to a functional group having a saltstructure such as a sulfonic acid salt group and generation of fog andthe like can be suppressed.

Further, in the case where toners are produced through a granulatingstep in an aqueous medium, use of resins having a sulfonic acid group ora sulfonic acid salt group causes a strong adverse influence ongranulability and hence the content thereof in the toner may be limitedin some cases. On the other hand, the resin having a sulfonic estergroup has little effect on granulability, so that its content in thetoner can be increased.

In addition, it has been confirmed that the effect of the sulfonic estergroup is exhibited remarkably by the aryl group. Presumably, this isbecause attachment of a sulfonic ester group through an aromatic ringresults in a change in the level of the molecular orbital of thesulfonic ester group by the conjugate system of the aromatic ring. Thearyl group is preferably a phenyl group or a naphthyl group.

Further, the aryl group may have other substituents, specific examplesof which include an alkyl group having 1 to 8 carbon atoms, an alkoxygroup having 1 to 8 carbon atoms, an acyl group, and an ester group.Further, the aryl group may form a 5-membered ring through adicarboxyanhydride or a dicarboxylmide at adjacent positions. Preferredexamples thereof include an alkyl group having 1 to 4 carbon atoms, ahydroxyl group, and an alkoxy group having 1 to 4 carbon atoms.

The bonding for coupling the aryl group to the resin is not particularlylimited but an amide bond, an ester bond, a urethane bond, a urea bond,and an ether bond are preferable taking into consideration the influenceon charging properties and production method. Of those, an amide bond, aurethane bond, and a urea bond are more preferable in view of theability of introducing the effect of extending the above-mentionedconjugate system. Further, the aryl group may be bonded by a single bondor may be incorporated into the main chain through two or more bonds.

When the bond for coupling is other than the amide bond, urethane bond,or urea bond, it is preferable that the aryl group have an amide group.Having an amide group as a substituent enables extension of theconjugate system.

The sulfonic ester group is not particularly limited but it is notpreferable in view of triboelectric charging properties that it be toobulky. Therefore, the sulfonic ester group preferably has the structureshown below:—SO₃R¹(wherein R¹ is an alkyl group having 1 to 12 carbon atoms or a phenylgroup), more preferably R¹ is an alky group having 1 to 8 carbon atoms,and still more preferably R¹ is an alkyl group having 1 to 4 carbonatoms.

Further, the aryl group containing the above-mentioned coupling portionpreferably has a structure shown by the following formulae (1) or (2)from the viewpoints that it is less bulky and provides bettertriboelectric charging properties. Further, the functional groups shownby the following formulae (1) or (2) are preferable since they are easyto commercially produce and excellent in cost performance.

(wherein R¹ to R⁴, independently, represent a hydrogen atom, an alkylgroup having 1 to 6 carbon atoms, a hydroxyl group, or an alkoxy grouphaving 1 to 6 carbon atoms, or R¹ to R⁴ at adjacent positions, takentogether, may form a benzene ring; and R⁵ represents an alkyl grouphaving 1 to 4 carbon atoms.)

(wherein R⁶ to R⁸, independently, represent a hydrogen atom, an alkylgroup having 1 to 6 carbon atoms, a hydroxyl group, or an alkoxy grouphaving 1 to 6 carbon atoms, or adjacent two of R⁶ to R⁸, taken together,may form a benzene ring at adjacent positions; and R⁹ represents analkyl group having 1 to 4 carbon atoms.)

Further, the aryl group containing the coupling portion is morepreferably a functional group having a structure shown by the followingformula (3). In the functional group having the structure, the hydrogenin —NH— and the oxygen in —SO₃R tend to be coupled through a hydrogenbond to extend the conjugate system, thus providing more excellenttriboelectric charging properties.

(wherein R¹⁰ to R¹³, independently, represent a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, a hydroxyl group, or an alkoxy grouphaving 1 to 4 carbon atoms and; and R¹⁴ represents an alkyl group having1 to 4 carbon atoms.)

In addition, the characteristic of the above-mentioned resin for toneris that it contains at least a polyester unit formed by polycondensationof a polyhydric alcohol component and a polycarboxylic acid component(hereinafter, referred to simply as “polyester unit”). Although detailedreason is unclear, it is presumed that the presence of an aryl grouphaving a negative sulfonic ester group in the polyester unit having astrong negative charge provides more stable triboelectric chargingproperties. Having the polyester unit makes it easy to controlcompatibility or non-compatibility with the binder resin. Controllingthe compatibility enables adjustment of the dispersibility of the resinfor toner in the toner in a macroscopic viewpoint of uniform dispersionor localization and in addition thereto control of the state of presenceof the resin for toner from the microscopic viewpoint of stretching ofmolecule or orientation of the functional group. This makes it easier tocontrol so that a desired triboelectric charging property can beobtained.

In addition, it is confirmed that when the toner particles are formed inwater, the effect of developing charge by the aryl group is notinhibited, the resin for toner tends to be localized near the surface ofthe toner, and better effect of improving the chargeability can beobtained. The reason that the resin for toner tends to be localized nearthe surface of the toner is presumed to be due to high polarities of thearyl group portion having a sulfonic ester group as a substituent andthe polyester unit.

Note that the resin having a polyester unit means a resin that hasportion having a polyester structure. Examples of the resin includepolyester resins and hybrid resins having a polyester unit and a vinylpolymer unit chemically bonded to each other.

Hereinafter, specific examples of the compounds used as the polyhydricalcohol component are given.

Examples of the dihydric alcohol components include: alkyleneoxideadducts of bisphenol A such aspolyoxypropylene-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-2,2-bis(4-hydroxyphenyl)propane,polyoxyethylene-2,2-bis(4-hydroxyphenyl)propane,polyoxypropylene-polyoxyethylene-2,2-bis(4-hydroxyphenyl)propane, andpolyoxypropylene-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol;diethylene glycol; triethylene glycol; 1,2-propylene glycol;1,3-propylene glycol; 1,4-butanediol; neopentyl glycol; 1,4-butenediol;1,5-pentanediol; 1,6-hexanediol; 1,4-cyclohexanedimethanol; dipropyleneglycol; polyethylene glycol; polypropylene glycol; polytetramethyleneglycol; bisphenol A; and hydrogenated bisphenol A.

Examples of the trihydric or higher alcohol components include sorbitol,1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol,tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol,2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane,trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

Hereinafter, specific examples of the compounds used as thepolycarboxylic acid component are given.

Examples of the dibasic carboxylic acid components include: aromaticdicarboxylic acids such as terephthalic acid, isophthalic acid,orthopthalic acid, naphthalenedicarboxylic acid, andbiphenyldicarboxylic acid; saturated or unsaturated aliphaticdicarboxylic acids such as oxalic acid, succinic acid, succinicanhydride, adipic acid, azelaic acid, sebacic acid, dodecanoic diacid,hydrogenated dimer acid, fumaric acid, maleic acid, maleic anhydride,itaconic acid, itaconic anhydride, citraconic acid, citraconicanhydride, and dimer acid; and alicyclic dicarboxylic acids such as 1,4

norbornenedicarboxylic acid and anhydrides thereof, tetrahydrophthalicacid and anhydrides thereof.

Examples of the tribasic or higher carboxylic acid components includetrimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid,trimellitic anhydride, pyromellitic anhydride,benzophenonetetracarboxylic acid anhydride, trimesic acid, ethyleneglycolbis(anhydrotrimelitate), glyceroltris(anhydrotrimelitate), and1,2,3,4-butanetetracarboxylic acid. Those polycarboxylic acid componentsmay be esters.

It is preferable that a catalyst be used in producing the polyesterunit. Examples of the catalyst include: tin-containing catalysts such asdioctyltin oxide, monobutyltin oxide, and dibutyltin oxide; alkyltitanates such as tetraethyl titanate, tetrapropyl titanate,acetyltripropyl titanate, tetrabutyl titanate, tetrahexyl titanate,2-ethylhexyl titanate, and polybutyl titanate; halogenated titaniumssuch as titaniumdichlorotitanium, trichlorotitanium,tetrachlorotitanium, trifluorotitanium, and tetrafluorotianium; titaniumketone enolates such as titanium acetylacetonate, titaniumdiisopropoxidebisacetylacetonate, and titanylacetylacetonate; andtitanium carboxylates such as aliphatic titanium monocarboxylate,aliphatic titanium dicarboxylate, aliphatic titanium tricarboxylate,tetrabasic or higher aliphatic titanium polycarboxylate, and aromatictitanium carboxylate.

The content proportion of the aryl group having a sulfonic ester groupas a substituent in the resin for toner will be explained. Theproportion of the aryl group contained in the resin preferably is 0.1 to0.9 mmol/g. If the proportion is less than 0.1 mmol/g, the chargingproperty of the resin tends to be insufficient while it is more than 0.9mmol/g, the dispersibility of the resin in the toner may be adverselyinfluenced or the developability/transferability of the toner may bedecreased.

Taking into consideration solubility in solvents and compatibility withthe resin for toner, compatibility with waxes, it is preferable that theresin for toner be a hybrid resin in which a vinyl polymer unit formedby polymerization of a vinyl monomer component and the polyester unitare bonded to each other.

The method of synthesizing the resin for toner of the present inventionis not particularly limited and the resin for toner can be produced bythe known techniques.

For example, there is a method in which upon forming the polyester unit,a component capable of polycondensation and having the above-mentionedaryl group is made coexist in mixture with the polycarboxylic acidcomponent and polyhydric alcohol component to introduce the aryl groupinto the main chain having the polyester unit. The “component capable ofpolycondensation” means a component that has two or more reactive groupssuch as a carboxylic group, a hydroxyl group, an amino group, and anisocyanato group in addition to the aryl group. Another method includes:forming a resin containing a polyester unit; and then bonding the arylgroup thereto as a side chain or a functional group by a polymericreaction. Further, in those methods, an aryl group having a sulfonicacid group instead of the sulfonic ester group can be introduced andthen the sulfonic acid in the resin can be esterified.

Further, as a specific synthetic method, a method of synthesizing aresin containing a polyester unit having the formula (3) above isexplained below.i) A method of incorporating a carboxylic acid into a resin having apolyester unit, condensing the carboxylic acid with an amine of thefollowing formula (4), and then esterifying the sulfonic acid group.

(wherein R¹⁵ to R¹⁸, independently, represent a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, a hydroxyl group, a methoxy group, oran ethoxy group.)ii) A method of incorporating a carboxylic acid into a resin having apolyester unit, and condensing the carboxylic acid with an amine of thefollowing formula (5).

(wherein R¹⁹ to R²², independently, represent a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, a hydroxyl group, a methoxy group, oran ethoxy group; and R²³ represents an alkyl group having 1 to 4 carbonatoms.)

Further, in the case of the hybrid resin, the following methods areexemplified.iii) A method of polymerizing a polyester having an unsaturated bond anda monomer component containing a monomer of the following formula (6),and then esterifying sulfonic acid.

(wherein R²⁴ to R²⁷, independently, represent a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, a hydroxyl group, a methoxy group, oran ethoxy group; and R²³ represents a methyl group or a hydrogen atom.)iv) A method of polymerizing a polyester having an unsaturated bond witha monomer component containing a monomer of the following formula (7).

(wherein R²⁹ to R³², independently, represent a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, a hydroxyl group, a methoxy group, oran ethoxy group; and R³³ represents an alkyl group having 1 to 4 carbonatoms; and R³ represents a methyl group or a hydrogen atom.)

Further, besides, a synthetic method of utilizing a polymer crosslinkingreaction through a urethane bond or a urea bond can also be used.

In the methods described in i) and ii) above, examples of the method ofincorporating a carboxylic acid to the resin having a polyester unitinclude a method of utilizing a carboxylic acid derived from apolyhydric carboxylic acid of the polyester unit and a method of forminga hybrid resin with a component having a carboxylic acid.

In the methods described in i) and ii) above, the method of condensingthe carboxyl group in the resin and an amine may be a known method. Forexample, a method in which triphenyl phosphite is reacted in an organicbase may be exemplified.

In the methods described in i) and iii) above, the method of esterifyingthe sulfonic acid group in the resin may be a known method. Specificexamples thereof include: a method of chlorinating a sulfonic acid andthen reacting the resultant with an alcohol; a method of using a methylesterifying agent such as dimethyl sulfate, trimethyl silyldiazomethane,trimethyl phosphate and so on; and a method of using an orthoformicester and so on. Of those, the method of using an orthoformic ester ispreferable. By this method, the esterification of the sulfonic acidgroup can be readily performed by reacting an orthoformic ester having adesired alkyl group with a resin containing a sulfonic acid underrelatively mild conditions, so that the ratio of esterification can bereadily controlled by the reaction temperature, reaction time, theamount of the orthoformic ester, the amount of the solvent and so on.

Specific examples of the orthoformic ester to be used in the presentinvention include trimethylorthoformate, triethylorthoformate,tri-n-propylorthoformate, tri-iso-propylorthoformate,tri-n-butylorthoformate, tri-sec-butylorthoformate,tri-tert-butylorthoformate, and mixtures thereof.

The method of synthesizing monomers represented by the formulae (6) and(7) above may be a known method. Example thereof includes a method ofamidating the amine represented by the formula (4) or (5) above with areactive acrylate (for example, acrylic acid chloride or methacrylicanhydride) and so on.

The vinyl monomer component that can be used is not particularly limitedwhen the resin for toner is the hybrid resin described above. Anaddition polymerization monomer is preferable. Specific examples of theaddition polymerization monomer include: styrenes such aso-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene,p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene,p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene,p-n-dodecylstyrene, and derivatives thereof; ethylenically unsaturatedmonoolefins such as ethylene, propylene, butylene, and isobutylene;unsaturated polyenes such as butadiene and isoprene; vinyl halides suchas vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl iodide;vinyl esters such as vinyl acetate, vinyl propionate, and vinylbenzoate; α-methylene aliphatic monocarboxylates such as methylmethacrylate, ethyl methacrylate, propyl methacrylate, n-octylmethacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearylmethacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, anddiethylaminoethyl methacrylate; acrylates such as methyl acrylate, ethylacrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octylacrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate,2-chloroethyl acrylate, and phenyl acrylate; vinyl ethers such as vinylmethyl ether, vinyl ethyl ether, and vinyl isobutyl ether; N-vinylcompounds such as vinyl methyl ketone, vinyl hexyl ketone, and methylisopropenyl ketone; vinylnaphthalenes; and acrylic acid derivatives suchas acrylonitrile, methacrylonitrile, and acrylamide.

The polymerization initiators that can be used when the monomercomponents as described above are copolymerized include varioussubstances such as peroxide polymerization initiators and azopolymerization initiators.

Examples of the peroxide polymerization initiators which can be usedinclude: organic peroxide polymerization initiators such as peroxyester,peroxydicarbonate, dialkylperoxide, peroxyketal, ketone peroxide,hydroperoxide, and diacylperoxide; and inorganic peroxide polymerizationinitiators such as persulfate and hydrogen peroxide.

Specific examples of the peroxide polymerization initiators include:peroxyester such as t-butyl peroxyacetate, t-butylperoxylaurate,t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate,t-butylperoxyisobutyrate, t-butylperoxyneodecanoate,t-hexylperoxyacetate, t-hexylperoxylaurate, t-hexylperoxypivalate,t-hexylperoxy-2-ethylhexanoate, t-hexylperoxyisobutyrate,t-hexylperoxyneodecanoate, t-butylperoxybenzoate,α,α′-bis(neodecanoylperoxy)diisopropylbenzene, cumylperoxyneodecanoate,1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate,1,1,3,3-tetramethylbutylperoxyneodecanoate,1-cyclohexyl-1-methylethylperoxyneodecanoate,2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane,1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate,t-hexylperoxyisopropylmonocarbonate,t-butylperoxyisopropylmonocarbonate,t-butylperoxy-2-ethylhexylmonocabonate, t-hexylperoxybenzoate,2,5-dimethyl-2,5-bis(benzoylperoxy)hexane,t-butylperoxy-m-toluoylbenzoate, bis(t-butylperoxy)isophthalate,t-butylperoxy maleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, and2,5-dimethyl-bis(m-toluoylperoxy)hexane; diacyl peroxides such asbenzoyl peroxide, lauroyl peroxide, and isobutyryl peroxide;peroxydicarbonates such as diisopropylperoxydicarbonate andbis(4-t-butylcyclohexyl)peroxydicarbonate; peroxyketals such as1,1-di-t-butylperoxycyclohexane, 1,1-di-hexylperoxycyclohexane,1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, and2,2,-di-t-butylperoxybutane; dialkyl peroxides such as di-t-butylperoxide, dicumyl peroxide, and t-butylcumyl peroxide; andt-butylperoxyallylmonocarbonate for another example. Further, examplesof the azo-based polymerization initiators which can be used include2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile,1,1′-azobis(cylohexane-1-carbonitrile),2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, andazobisisobutyronitrile.

Note that two or more of those polymerization initiators may be usedsimultaneously as necessary.

In this case, the quantity of the polymerization initiators used ispreferably 0.1 to 20 parts by mass with respect to 100 parts by mass ofthe monomer.

As the polymerization method, any of a solution polymerization method, asuspension polymerization method, an emulsion polymerization method, adispersion polymerization method, a precipitation polymerization method,a bulk polymerization method, and so on may be used and is notparticularly limited.

When the molecular weight of the resin for toner is too small, memberssuch as a sleeve and a carrier tend to be contaminated. In addition, thecharging property of the aryl group may be adversely affected. On thecontrary, when the molecular weight of the resin for toner is too large,not only there is the possibility that the fixability of the toner willbe deteriorated but also the state of the resin for toner in the toneris unstable, so that uniform charging property can not be exhibited.From those viewpoints, the molecular weight of the resin for toner bepreferably 2,000 to 200,000 in terms of weight average molecular weightas calculated by gel permeation chromatography. A more preferred rangeis a weight average molecular weight of 5,000 to 100,000.

Further, it is preferable that the molecular weight distribution of theresin for toner be narrow from the viewpoints of charging property andfixability. A preferable molecular weight distribution range is suchthat the ratio (Mw/Mn) of the weight average molecular weight (Mw) tothe number average molecular weight (Mn), calculated by gel permeationchromatography (GPC) is preferably 1.0 to 6.0, more preferably 1.0 to4.0.

The measurement of molecular weight by GPC can be performed as follows.

Each resin sample is added to THF (tetrahydrofuran) and the mixture isleft to stand at room temperature for 24 hours. The obtained solution isfiltered through a solvent-resistant membrane filter having a porediameter of 0.2 μm to obtain a sample solution, which is measured underthe following conditions. Note that when preparing samples, the amountof THF is adjusted such that the concentration of the resin for toner is0.4 to 0.6 mass %.

Apparatus: High performance GPC HLC8120 GPC (manufactured by Tosoh)

Column: Seven sequences of Shodex KF-801, 802, 803, 804, 805, 806, 807(manufactured by Showa Denko K. K)

Eluant: Tetrahydrofuran

Flow rate: 1.0 ml/min

Oven temperature: 40.0° C.

Amount of sample injected: 0.10 ml

Further, upon calculation of the molecular weight of samples, amolecular weight calibration curve prepared using standard polystyreneresins (TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40,F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500 manufactured byTosoh) is used.

To exhibit effects without deteriorating the fixability of the toner, itis preferable that the glass transition temperature (Tg) of the resinfor toner be controlled and Tg measured using a differential scanningcalorimeter (DSC) is preferably 45° C. to 90° C., more preferably 50° C.to 85° C.

To improve the compatibility with the binder resin and further localizethe resin for toner near the surface of the toner when producing tonerparticles in an aqueous medium, it is preferable that the resin fortoner have a specified acid value. However, when the acid value is toohigh, the charging property of the aryl group may be inhibited and thechargeability of the toner may be influenced by a change in theenvironment (temperature and humidity), so that high acid values areundesirable. A preferable range of the acid value of the resin for toneris 0.1 to 40.0 mgKOH/g, more preferably 2.0 to 30.0 mgKOH/g.

The acid value in the present invention is obtained by the followingmethod.

Basic operations are based on JIS K-0070.

1) 0.5 to 2.0 g of pulverisates of a sample was precisely weighed. Theweight obtained is defined as W (g).

2) The sample is charged in a 300-ml-beaker, and 150 ml of a mixedliquid of toluene/ethanol (4/1) is added to dissolve the sample.

3) Using a 0.1 mol/l ethanol solution of KOH, titration is performedusing a potentiometric titrator (automatic titration may be used with,for example, a potentiometric titrator AT-400 (winwork station) and anABP-410 electrically driven biuret manufactured by Kyoto Electric Co.,Ltd.).

4) The quantity of the KOH solution used on this occasion is defined asS (ml). Simultaneously, blank is measured to define the quantity of thisKOH solution used on this occasion as B (ml).

5) Acid value is calculated by the following equation. f is a factor ofKOH.

Acid value (mgKOH/g)={(S−B)×f×5.61}/W

The toner of the present invention contains a binder resin, a colorant,and the above-mentioned resin for toner.

A preferable range of the content of the resin for toner is 0.1 to 20parts by mass, more preferably 0.3 to 10 parts by mass with respect to100 parts by mass of the binder resin.

The binder resin that is used in the present invention is notparticularly limited. Examples thereof include styrene resins, acrylicresins, styrene-acrylic resins, styrene-methacrylic resins, polyethyleneresins, polyethylene-vinyl acetate resin, vinyl acetate resins,polybutadiene resins, phenol resins, polyurethane resins, polybutyralresins, and polyester resins. Of those, styrene resins, acrylic resins,styrene-acrylic resins, styrene-methacrylic resins, and polyester resinsare preferable.

The binder resin preferably has a peak molecular weight of 3,000 to80,000 as calculated by GPC of THF-soluble component. If the molecularweight is smaller than 3,000, the chargeability may cause a problem. Onthe other hand, if the molecular weight of the binder resin is largerthan 80,000, low temperature fixation becomes difficult. Note that themethod of measuring the peak molecular weight is the same as the methodof measuring the molecular weight of the resin for toner as describedabove.

The toner preferably contains waxes. Waxes contained enable one toprovide a toner having excellent low temperature fixability andanti-offset property. Further, in the method of forming an image using atoner containing waxes, a fixed image having excellent surfacesmoothness can be obtained.

When the toner contains a wax, the molten wax upon fixation acts as arelease agent between a transfer material and a fixing member due to itssurface tension and significantly improves anti-offset performance.Also, by accelerating melting of the toner upon fixation, lowtemperature fixability can also be improved. Waxes showing a main peakin 45° C. to 130° C., more preferably 50° C. to 110° C., and still morepreferably 50° C. to 90° C. in a DSC curve when elevating thetemperature of the toner as measured on a differential scanningcalorimeter are advantageous. If the main peak temperature is too high,the releasing action at low temperatures does not appear, so that thetoner tends to have a poor fixability. On the contrary, if the main peaktemperature is too low, the melt viscosity of the toner becomes too low,so that no releasing action occurs on the higher temperature side andsufficient anti-offset property is difficult to obtain. Thus, tonercauses the phenomena of transfer-material-winding-about or-attachment tothe fixing member to occur.

It is preferable that a wax be contained in an amount within the rangeof 0.5 to 30 parts by mass with respect to 100 parts by mass of thebinder resin. If the content is less than 0.5 parts by mass, the effectof improvement in anti-offset property described above becomesinsufficient. On the other hand, if the content of the wax is more than30 parts by mass, it causes that long term storage stability isdecreased and inhibits dispersion of other toner materials. Further,since the amount of wax present near the surface of the toner increases,the flowability of the toner is decreased, resulting in a decrease inimage properties.

The waxes that can be used in the present invention are not particularlylimited as long as they may be any that has a heat absorption main peakwithin the above-mentioned range. Specific examples thereof includeparaffin wax, microcrystalline wax, petroleum waxes such as petrolatumand derivatives thereof, montan wax and derivatives thereof, hydrocarbonwaxes and derivatives thereof by a Fisher-Tropsch method, polyolefinwaxes and derivative thereof represented by polyethylene, natural waxessuch as carnauba wax and candelilla wax and derivatives thereof. Notethat the derivatives include oxides, block copolymers with vinylmonomers, and graft modified products. Further, waxes include, forexample, higher aliphatic alcohols, fatty acids such as stearic acid andpalmitic acid, or compounds thereof, acid amide waxes, ester waxes,ketones, hardened castor oil and derivatives thereof, vegetable waxes,and animal waxes.

As described above, to obtain toners that have excellent fixability, itis preferable that the glass transition temperature of the toner be alsocontrolled. The glass transition temperature of the toner obtained fromthe DSC curve is preferably 45 to 70° C., more preferably 50 to 70° C.By controlling the glass transition temperature of the toner to bewithin the above-mentioned range, excellent low temperature fixationperformance and anti-blocking property can be obtained. Further, underhigh temperature environment, fusion adhesion of toner to the developingdevice and mutual fusion between toners can be suppressed to prevent adecrease in flowability.

In the present invention, the fusion peak of the wax, softeningtemperature of the toner, and glass transition temperature can bemeasured using, for example, a differential scanning calorimetric (DSC)apparatus (M-DSC manufactured by TA Instruments Co.). The measuringmethod involves precision weighing about 6 mg of a sample in an aluminumpan, using a vacant aluminum pan as a reference pan, and performingmeasurement in a nitrogen atmosphere at a modulation amplitude of ±0.6°C. and a frequency of 1/minute. From a reversing heat flow curve whenelevating the temperature, a glass transition temperature is obtained bya midpoint method. The fusion peak is obtained from the heat flow curveobtained in the above-mentioned measurement.

The toner of the present invention contains a colorant.

As a black colorant, there can be utilized carbon black, a magneticmaterial, and a mixture of the following yellow/magenta/cyan colorantsadjusted to black color.

The yellow colorants that can be used include as pigments, thosecompounds represented by condensed azo compounds, isoindolinonecompounds, anthraquinone compounds, azo metal complex methine compounds,and arylamide compounds. Specific examples of the yellow colorantsinclude C.I. Pigment Yellow 3, 7, 10, 12, 13, 14, 15, 17, 23, 24, 60,62, 74, 75, 83, 93, 94, 95, 99, 100, 101, 104, 108, 109, 110, 111, 117,123, 128, 129, 138, 139, 147, 148, 150, 166, 168, 169, 177, 179, 180,181, 183, 185, 191:1, 191, 192, 193, and 199. Examples of the dye-basedyellow colorants include C.I. Solvent Yellow 33, 56, 79, 82, 93, 112,162, and 163, and C.I. Disperse Yellow 42, 64, 201, and 211.

As the magenta colorants, there are used condensed azo compounds,diketopyrrolopyrrole compounds, anthraquinone, quinacridone compounds,basic dye lake compounds, naphthol compounds, benzimidazolone compounds,thioindigo compounds, and perylene compounds. Specifically, C.I. PigmentRed 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 146, 166, 169,177, 184, 185, 202, 206, 220, 221, and 254, and C.I. Pigment Violet 19are particularly preferable.

As the cyan colorants, there are used copper phthalocyanine compoundsand derivatives thereof, anthraquinone compounds, and basic dye lakecompounds. Specifically, C.I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3,15:4, 60, 62, and 66 are particularly preferably used.

Those colorants can be used alone or in admixture, or further in a solidsolution state. The colorants are selected in light of hue angle, chromasaturation, luminance, weatherability, OHP transparence, dispersibilityin toners. The colorant is added in amounts of 1 to 20 parts by masswith respect to 100 parts by mass of the binder resin.

Further, the toner of the present invention may contain a magneticmaterial so that it can be used as a magnetic toner. In this case, themagnetic material may serve as a colorant as well. Examples of themagnetic material include iron oxides such as magnetite, hematite, andferrite; metals such as iron, cobalt, and nickel, or alloys of thosemetals with other metals such as aluminum, cobalt, copper, lead,magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium,manganese, selenium, titanium, tungsten, and vanadium, and mixturesthereof.

The magnetic materials used in the present invention are more preferablysurface-modified magnetic materials. When used in polymerization tonersobtained by a production method such as a polymer melt suspension methodor a suspension polymerization method, it is preferable that themagnetic material is subjected to hydrophobic treatment with a surfacemodifier that is a substance having no inhibition on polymerization. Thesurface modifiers include, for example, silane coupling agents andtitanium coupling agents.

The magnetic materials are preferably those having number averageparticle diameter of 2 μm or less, preferably about 0.1 to about 0.5 μm.The amount of the magnetic material to be contained in the toner ispreferably 20 to 200 parts by mass, particularly preferably 40 to 150parts by mass, with respect to 100 parts by mass of the binder resin.

Magnetic materials that have magnetic properties when applied 796 kA/m(10 kOe), i.e., a coercive force (Hc) of 1.59 to 23.9 kA/m (20 to 300Oe), a strength of magnetization (σ_(10k)) of 50 to 200 emu/g, aresidual magnetization (σr) of 2 to 20 emu/g are preferable.

To develop more minute latent dots reliably for obtaining a higher imagequality, it is preferable that the toner have a weight average particlediameter of 3.0 to 9.0 μm, more preferably 4.0 to 6.5 μm. When theweight average particle diameter of the toner is within theabove-mentioned range, good transfer efficiency can be obtained, so thatthe scraping of the photosensitive member and fusion of the toner can besuppressed and also good flowability can be maintained. Therefore,occurrence of fog and a decrease in transferability can be suppressed.Further, formation of black spots around character or line images can besuppressed, so that high resolution images can be obtained.

The weight average particle diameter and particle diameter distributionof the toner can be measured by various methods such as those using aCoulter counter® TA-II Model or Coulter Multisizer™ (manufactured byCoulter, Inc.). In the present invention, Coulter Multisizer™ is used inconnection with an interface (manufactured by Nikkaki Co., Ltd.) thatoutputs number distribution or volume distribution and PC9801 personalcomputer (manufactured by NEC Corporation). As the electrolyte, 1% NaClaqueous solution is prepared using first-grade sodium chloride. Theelectrolytes that can be used include, for example, ISOTON R-II(manufactured by Coulter Scientific Japan). The measuring method is asfollows. That is, 0.1 to 5 ml of a surfactant (preferablydodecylbenzenesulfonic acid sodium salt) as a dispersant and further 2to 20 mg of a sample to be measured is added to 100 to 150 ml of theaqueous electrolyte solution. The electrolyte having dispersed thereinthe sample is dispersed for about 1 to 3 minutes with an ultrasonicdispersion machine, and the resultant is measured for volume and numberof toner particles of 2.0 μm or more with the Coulter Multisizer™ usingan aperture 100 μm as its aperture to calculate volume distribution andnumber distribution, from which weight average particle diameter (D4) isdetermined.

The average circularity of the toner is preferably 0.955 or more.Particularly preferably, the average circularity of the toner is 0.970or more. When the average circularity of the toner is high, asynergistic effect with the resin for toner is exhibited to promoteuniform chargeability, thus providing a toner having very excellenttransferability. Presumably, this is because the contact area of thetoner particles with the photosensitive member is small and the adhesiveforce of the toner particles onto the photosensitive member due tomirror force or van der Waals force is decreased and in addition, localovercharging is suppressed.

In the present invention, the average circularity is used as a simplemeans for quantitatively expressing the shape of particles. In thepresent invention, measurement is performed by using a flow-typeparticle image measuring apparatus “FPIA-3000 Model” (manufactured bySysmex Corporation) that has a resolution of 0.37 Um per pixel and takesa picture of 512 pixel×512 pixel for analysis, and a circularity of themeasured particle is obtained by the following equation, and further avalue obtained by dividing the sum of circularities of all the particlesdetermined by the total number of the particles as shown in thefollowing equation is defined as an average circularity.Circularity C=Circumferential length of a circle having the same area asa projection area of a particle/Circumferential length of projectionimage of a particle${{Average}\quad{circularity}\quad\overset{\_}{C}} = {\sum\limits_{i = 1}^{m}\left( {C_{i}/m} \right)}$

Note that in the present invention, an average circularity is determinedas follows. That is, particle analysis is performed using “FPIA-3000” ata digitization threshold of 85% to obtain circularities. Then, theobtained circularities are assigned particle after particle torespective channels obtained by dividing a range of circularity of 0.40to 1.00 by 800, and the average circularity is calculated using thecenter values and frequencies of the channels. More specifically, themeasuring method is performed as follows. That is, after a suitableamount of a surfactant, preferably dodecylbenzenesulfonic acid sodiumsalt as a dispersant is added to 20 ml of deionized water, 0.02 g of asample to be measured is added and the resultant mixture is subjected todispersing treatment for 2 minutes using a desk-top type ultrasonicwasher disperser (for example, “VS-150” manufactured by Velvo-Clear Co.,Ltd.) at an oscillation frequency of 50 kHz and electric output of 150 Wto obtain a dispersion for measurement. On this occasion, the dispersionis cooled as appropriate so that the temperature of the dispersion is10° C. or more and 40° C. or less.

For the measurement, the above-mentioned flow-type particle imagemeasuring apparatus having mounted thereon a standard objective lens (10times) is used and Particle Sheath “PSE-900A” (manufactured by Sysmex)is used as a sheath fluid. The dispersion prepared according to theabove-mentioned procedure is introduced into the flow-type particleimage measuring apparatus and 3,000 particles are measured in a totalcount mode with limiting the analysis particle diameter to acircle-corresponding diameter of 2.00 μm or more and 200.00 μm or lessto obtain an average circularity of the toner.

Upon measurement, automatic focus adjustment is performed using standardlatex particles (for example, 5200A manufactured by Duke ScientificCorporation, diluted with deionized water) in advance. Then, it ispreferable that focus adjustment be performed for every two hours fromthe start of measurement.

Note that, in the examples of the present invention, measurements wereperformed using a flow-type particle image measuring apparatus on whichcorrection operation was performed by Sysmex Corporation and aCorrection Certificate by Sysmex Corporation was issued under the samemeasurement and analysis conditions except that analysis particlediameter was limited to a circle-corresponding diameter of 2.00 μm ormore and 200.00 μm or less.

The “circularity” in the present invention is a measure of the degree ofthe irregularities of a toner particle. When a toner particle is of acompletely spherical shape, the circularity is 1.000. The morecomplicated a surface shape, the lower the circularity.

Generally, toners having an amorphous shape have low charge uniformityat protruded portions or depressed portions of the toner. Moreover, thetoners have an increased contact area between the photosensitive member(electrostatic latent image bearing member) and the toner because ofbeing amorphous, resulting in a high toner attraction force, to cause anincrease in transfer residual toner.

The toner may contain other charge control agents as necessary to aidits triboelectric property. Specifically, the charge control agent thatcan be contained include negative-type control agents such as metalcompounds of salicylic acid, alkyl salicylic acid, dialkylsalicylicacid, naphthoic acid, and dicarboxylic acid; high polymer compoundshaving a sulfonic acid or carboxylic acid in the side chain; boroncompounds; urea compounds; silicon compounds; and calixarene; andpositive-type control agents such as quaternary ammonium salts, highpolymer compounds having the quaternary ammonium salt in the side chainthereof, guanidine compounds, and imidazole compounds.

The method of producing the toner is not particularly limited and knownproduction methods are used. Specifically, methods that produce tonerparticles directly using suspension polymerization methods described inJapanese Patent Publication No. S36-10231, Japanese Patent ApplicationLaid-Open Nos. S59-53856 and S59-61842; methods that produce tonerparticles by an interfacial polymerization method such as microcapsuleproduction method; toner formation by a coacervation method; a method offorming toner particles by an association polymerization method thatmakes at least one type fine particles coagulate to provide particles ofa desired particle size as disclosed in Japanese Patent ApplicationLaid-Open Nos. S62-106473 and S63-186253; a method of producing tonerparticles by a dispersion polymerization method characterized bymonodispersion; a polymer dissolution (melting) suspension method thatinvolves dissolving necessary resins in a water-insoluble organicsolvent and then forming toner particles in water; a method of preparingtoner particles by an emulsion dispersion method; and a pulverizationmethod that involves kneading toner components to disperse themuniformly using a compression kneader, an extruder or a media dispersionmachine, cooling the kneaded mixture, pulverizing the cooled kneadedmixture mechanically or by making the mixture collide against a targetunder a jet stream to a desired toner particle size, and classifying thetoner particles to produce a toner having a sharpened particle diameterdistribution; and a method of providing toner particles by subjectingthe toner obtained by the pulverization method to spheronizationtreatment, for example, by heating it in a solvent.

However, the method that exhibits the effect of adding the resin fortoner of the present invention more significantly is a polymerdissolution (melting) suspension method or a suspension polymerizationmethod. This is because in the step of granulation, in an aqueous medium(granulation step), the resin for toner can be effectively localizednear the surface of the toner particles. Hereinafter, each suspensionmethod is explained.

In the method of producing toner particles by a polymer dissolution(melting) suspension method, first a binder resin, a resin for toner,and a colorant are dissolved and mixed or dispersed in an organicmedium, or a resin for toner and a colorant are dissolved and mixed ordispersed in a resin that is molten with heat. Further, the resultanttogether with wax and other additives as necessary is uniformlydissolved and mixed or dispersed using an agitator or the like toprepare a liquid mixture for forming a toner. On this occasion, acolorant, wax and other additives are melt-kneaded in advance and theresultant may be added. The liquid mixture thus obtained is added in adispersed medium (preferably an aqueous medium) containing a dispersionstabilizer and dispersed and suspended to a toner particle size using ahigh speed dispersion machine such as a high speed agitator or anultrasonic dispersion machine as an agitating apparatus (agitatingstep). Then, in the case where an organic solvent is used to dissolvethe binder resin, the organic solvent is removed by heating or pressurereduction and a solvent such as methanol, ethanol, 1-propanol, t-butylalcohol, or acetone is added to completely remove the organic solvent toobtain toner particles.

In the method of producing toner particles by a suspensionpolymerization method, first a colorant is uniformly dissolved and mixedor dispersed in a portion of polymerizable monomer or a total amount ofthe polymerizable monomer using an agitator or the like. In particular,when the colorant is a pigment, it is preferable that a portion of thepolymerizable monomer and the pigment be treated in a dispersion machineto form a pigment-dispersed paste and the resultant is finely dissolvedand mixed or dispersed together with the remaining polymerizablemonomer, a resin for toner, and a polymerization initiator as well aswax and other additives as necessary in an agitator to prepare a monomercomposition. The thus obtained monomer composition is added to adispersed medium (preferably an aqueous medium) containing a dispersionstabilizer and is finely dispersed until it comes into a toner particlesize using a high speed dispersion machine such as a high speed agitatoror an ultrasonic dispersion machine as an agitating apparatus(granulation step). Then, the monomer composition finely dispersed issubjected to polymerization reaction with light or heat in thepolymerization step and thus a toner can be obtained.

The organic medium that can be used in the polymer dissolution (melting)suspension method may be determined depending on the toner binder resinand is not particularly limited. Specifically, it is selected from etheralcohols such as methyl cellosolve, cellosolve, isopropyl cellosolve,butyl cellosolve, diethylene glycol, and monobutyl ether; ketones suchas acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters suchas ethyl acetate, butyl acetate, ethyl propionate, and cellosolveacetate; hydrocarbons such as hexane, octane, petroleum ether,cyclohexane, benzene, toluene, and xylene; halogenated hydrocarbons suchas trichloroethylene, dichloromethane, and chloroform; ethers such asethyl ether, dimethyl glycol, and trioxanetetrahydrofuran; acetals suchas methylal and diethyl acetal; sulfur/nitrogen-containing organiccompounds such as nitropropene, nitrobenzene, and dimethyl sulfoxide.

The method of dispersing a pigment composition in an organic medium maybe a known method. For example, a resin, a pigment dispersant aredissolved as necessary in an organic medium and while agitating theresulting mixture, a pigment powder is gradually added thereto andallowed to blend in the solvent sufficiently. Further, the pigment canbe finely dispersed in the mixture stably, that is, in the form of fineparticles by applying a mechanical shearing force to the mixture by adispersion machine such as a ball mill, a paint shaker, a dissolver, anattriter, a sand mill, or a high speed mill.

The resin as a binder resin for use in the polymer dissolution (melting)suspension method is not particularly limited. Examples thereof includestyrene resins, acrylic resins, methacrylic resins, styrene-acrylicresins, styrene-methacrylic resins, styrene acrylic resin-methacrylicresins, polyethylene resins, polyethylene-vinyl acetate resins, vinylacetate resins, polybutadiene resins, phenol resins, polyurethaneresins, polybutyral resins, and polyester resins. Of those, styreneresins, acrylic resins, styrene-acrylic resins, styrene-methacrylicresins, styrene-acrylic resin-methacrylic resins, and polyester resinsare preferable in view of the toner properties.

The polymerizable monomer that can be used advantageously in thesuspension polymerization method is an addition polymerizable monomer ora condensation polymerization monomer and those exemplified as monomersthat can be used in the above-mentioned production method for hybridresins can be used.

The dispersion medium that can be used in the above-mentioned productionmethod is determined depending on the solubilities of the binder resin,organic medium, monomer and resin for toner in the dispersion medium,and an aqueous medium is preferable. Examples of the aqueous medium thatcan be used include water; alcohols such as methyl alcohol, ethylalcohol, denatured ethyl alcohol, isopropyl alcohol, n-butyl alcohol,isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, tert-amylalcohol, 3-pentanol, octyl alcohol, benzyl alcohol, and cyclohexanol;ether alcohols such as methyl cellosolve, cellosolve, isopropylcellosolve, butyl cellosolve, and diethylene glycol monobutyl ether.Besides, the dispersion medium may be selected from water-soluble mediathat include ketones such as acetone, methyl ethyl ketone, and methylisobutyl ketone; esters such as ethyl acetate, butyl acetate, ethylpropionate, and cellosolve acetate; ethers such as ethyl ether anddiethylene glycol; acetals such as methylal and diethyl acetal; acidssuch as formic acid, acetic acid, and propionic acid;sulfur/nitrogen-containing organic compounds such as nitropropene,nitrobenzene, dimethylamine, monoethanolamine, pyridine, dimethylsulfoxide, and dimethylformamide. The dispersion medium is particularlypreferably water or alcohols. Two or more of those solvents may be usedin admixture. The concentration of the liquid mixture or monomercomposition to the dispersed medium is preferably 1 to 80 mass % andmore preferably 10 to 65 mass %.

The dispersion stabilizers that can be used when the aqueous dispersedmedium is used may be known ones. Specific examples of inorganiccompounds as a dispersion stabilizer include calcium phosphate,magnesium phosphate, aluminum phosphate, zinc phosphate, calciumcarbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide,aluminum hydroxide, calcium metasilicate, calcium sulfate, bariumsulfate, bentonite, silica, and alumina. Examples of the organiccompounds as a dispersion stabilizer include polyvinyl alcohol, gelatin,methylcellulose, methylhydroxypropylcellulose, ethylcellulose,carboxymethylcellulose sodium salt, polyacrylic acid and salts thereof,and starch. Those can be used by dispersing them in an aqueous phase.The concentration of the dispersion stabilizer is preferably 0.2 to 20parts by mass with respect to 100 parts by mass of the liquid mixture ormonomer composition.

The polymerization initiator used when the toner is produced by asuspension polymerization method may include known polymerizationinitiators. Specifically, the polymerization initiators exemplified aspolymerization initiators that can be used in the production method ofthe above-mentioned hybrid resins.

The chain transfer agent that can be used when the toner is produced bythe suspension polymerization method may be a known chain transferagent.

For improving the flowability of the toner and achieving uniformcharging of the toner, it is preferable that an inorganic fine powder beapplied to a surface of the toner particles.

The inorganic fine powder preferably has a number average primaryparticle diameter of 4 to 80 nm. To make the charge distribution oftoner particles more uniform, it is more preferable that the inorganicfine powder have a number average primary particle diameter of 6 to 35nm. When the number average primary particle diameter of the inorganicpowder is in the above-mentioned range, good flowability tends to beobtained and uniform charge tends to be obtained.

In the present invention, the number average primary particle diameterof the inorganic fine powder can be measured by counting 100 or moreprimary particles of inorganic fine powder that are present as attachedon the surface of the toner particles or in a free state in a photographof the toner taken by a scanning electron microscope in an magnifiedscale and calculating a number average particle diameter from thecounts. Note that to perform measurement while confirming the type ofthe particles, measurement is performed referring to a photograph of thetoner surface mapped with an element contained in the inorganic finepowder by an elemental analysis means such as XMA annexed to thescanning electron microscope.

The inorganic fine powders that can be used include inorganic finepowder selected from silica, alumina, and titania or double oxidesthereof. The double oxides include, for example, aluminum silicate finepowder and strontium titanate fine powder. As the silicate fine powder,both dry silicas such as a so-called dry method silica or hummed silicaand a so-called wet method silica that is produced from water glass orthe like can be used. The dry silica, which contains less silanol groupson the surface and inside the silicate fine powder and less productionresidues such as Na₂O and SO₃ ²⁻ is more preferable than the others. Inthe case of dry silica, for example, other metal halide compounds suchas aluminum chloride and titanium chloride may be used together with thesilicon halide compound in the production process to provide complexfine powder derived from silica and other metal oxide compounds. The drysilica used in the present invention includes this.

The inorganic fine powder having a number average primary particlediameter of 4 to 80 nm is preferably added in an amount of 0.1 to 5.0parts by mass with respect to 100 parts by mass of the toner particles.When the addition amount of the inorganic fine powder is less than 0.1parts by mass, its effect is insufficient while it is more than 5.0parts by mass, the fixability of the toner may be decreased.

While the inorganic fine powder is added for improving the flowabilityof the toner and for uniform charging of the toner particles, in apreferred embodiment, the inorganic fine powder may be subjected, forexample, to a hydrophobizing treatment to adjust the charge quantity ofthe toner and impart the toner with the function of improving theenvironment stability.

When the inorganic fine powder that is added to the toner absorbsmoisture, the charge quantity of the toner particles significantlydecreases to readily cause scattering of the toner.

The hydrophobizing agent that hydrophobizes the inorganic fine powderthat can be used include silicone varnishes, various denatured siliconevarnishes, silicone oils, various denatured silicone oils, silanecompounds, silane coupling agents, and other organosilicon compounds,organotitanium compounds and the like treating agents. Those can be usedalone or in combination for the treatment.

Of those, those treated with the above-mentioned silicone oils arepreferable. More preferably, use of the inorganic fine powder subjectedto treatment with a silicone oil simultaneous with or afterhydrophobizing treatment as a magnetic toner particle is advantageousfor maintaining the charge quantity of the toner particles at highlevels under high humidity conditions to prevent scattering of thetoner.

Further, in a preferable embodiment, the toner may containnear-spherical inorganic fine particles or organic fine particles havinga primary particle diameter of more than 30 nm (preferably having aspecific surface area of less than 50 m²/g), more preferably 50 nm(preferably having a specific surface area of 30 m²/g). Specifically,for example, spherical silica particles, sphericalpolymethylsilsesquioxane particles, spherical resin particles and so oncan be preferably used.

Further, the toner may contain other additives, for example, lubricantpowders such as TEFLON (registered trademark) powder, zinc stearatepowder, and polyvinylidene fluoride powder, polishing agents such ascerium oxide powder, silicon carbide powder, and strontium titanatepowder, flowability imparting agents such as titanium oxide powder andaluminum oxide powder, caking preventing agents, or organic and/orinorganic fine particles of opposite polarity as development improvingagents in small amounts as far as they give substantially no adverseinfluences.

Further, the toner of the present invention can be used either inadmixture with a carrier as a two-component developer or as asingle-component developer consisting of toner alone. In particular,when the toner is used as a nonmagnetic single-component developer forwhich charge rising property is important, the toner can exhibit sucheffect more significantly.

EXAMPLE

Hereinafter, the present invention is explained concretely by way ofexamples. However, the present invention should not be construed asbeing limited to the examples. All parts used in the examples are bymass.

Analyzing appliances used in the examples are as follows.

—FT-IR Spectrum

AVATAR 360 FT-IR, manufactured by Nicolet Corporation

—¹H-NMR, ¹³C-NMR

FT-NMR JNM-EX400 manufactured by JEOL, Ltd. (solvent used: heavychloroform)

—Elemental Analysis

Elemental analysis apparatus EA-1108 manufactured by Carlo Erba(calculate amounts of C, O, S, and N)

<<Synthesis of Resin Component>>

<Production of Polyester PA>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 66.1 parts of a 2mole propylene oxide adduct of bisphenol A, 33.9 parts of dimethylterephthalate, and 2.0 parts of potassium titanyl oxalate as acondensation catalyst and the mixture was allowed to react at 230° C.for 10 hours under nitrogen stream with distilling off water formed.Then, the reaction mixture was allowed to react under reduced pressureof 5 to 20 mmHg. The reaction mixture was take out when the hydroxylvalue thereof reached 50 mgKOH/g or more to obtain a polyester resin.The polyester resin contained no THF-insoluble matter and had an acidvalue of 0 mgKOH/g, a hydroxyl value of 54 mgKOH/g, Tg of 54° C., Mn of1,780, and Mw of 3,950.

To a solution of 20 parts of the obtained polyester resin dissolved in80 parts of methoxybutyl acetate was dropwise added a mixture of 3.0parts of 2-methacryloyloxyethyl isocyanate, 0.03 parts of dibutyltinlaurate, and 10 parts of methoxybutyl acetate. The reaction wascontinued until the peak of isocyanate at 2,200 cm⁻¹ disappeared whilethe progress of reaction was being monitored by IR (infrared absorptionspectrum). The reaction mixture was dropwise added to hexane to carryout purification by reprecipitation. After filtration, the residue wasdried under reduced pressure to obtain a polyester resin PA havingunsaturated bonds at both ends thereof.

<Production of Polyester PB>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 26.6 parts ofpropylene glycol, 103.8 parts of terephthalic acid, 9.7 parts of adipicacid, 23.5 parts of maleic anhydride, and 2.0 parts of tetrastearyltitanate as a condensation catalyst and the mixture was allowed to reactat 230° C. for 6 hours under nitrogen stream with distilling offgenerated water. Then, the reaction mixture was allowed to react under areduced pressure of 5 to 20 mmHg for 8 hours to obtain an unsaturatedpolyester resin PB. The polyester resin PB contained no THF-insolublematter and had an acid value of 15.0 mgKOH/g, a hydroxyl value of 61.0mgKOH/g, Tg of 47.2° C., Mn of 1,900, and Mw of 3,900.

<Production of Hybrid Resin HA>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of xyleneand 60 parts of polyester resin PB and the mixture was agitated at 50°C. under a nitrogen stream.

Then, the following monomers were mixed to prepare a monomer mixedliquid. 2-Ethylhexyl acrylate 5.0 parts Styrene 27.5 parts Acrylic acid7.5 parts

Further, the monomer mixed liquid was mixed with 1.6 parts of t-butylperoxyisopropylmonocarbonate (Perbutyl I, manufactured by NOFCORPORATION.) as a ploymerization initiator and the mixture was droppedto the reaction vessel and the temperature was elevated to 120 to 125°C. Under reflux conditions, the reaction mixture was stirred for 6 hoursand cooled to room temperature. Thereafter, the polymerization solutionwas dropwise added to 600 parts of hexane to perform reprecipitation forpurification and the obtained polymer was washed with 200 parts ofhexane twice. After filtration, the residue was dried at 40° C. underreduced pressure to obtain resin powder. This was named hybrid resin HA.The hybrid resin HA contained no THF-insoluble matter and had an acidvalue of 73.4 mgKOH/g, a hydroxyl value of 36.6 mgKOH/g, Tg of 53.5° C.,Mn of 2,800, and Mw of 7,900.

<Production of Polyester Resin PC>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 70.0 parts of 2 molepropylene oxide adduct of bisphenol A, 25.0 parts of terephthalic acid,5.0 parts of trimellitic anhydride, and 2.0 parts of potassium titanyloxalate and the mixture was allowed to react at 230° C. for 10 hoursunder nitrogen stream with distilling off generated water. Then, thereaction mixture was allowed to react under reduced pressure of 5 to 20mmHg. The polymer was taken out when the acid value reached 25 to obtaina polyester resin PC. The polyester resin PC contained 9.0 mass % of aTHF-insoluble matter and had an acid value of 24.5 mgKOH/g, a hydroxylvalue of 33.0 mgKOH/g, Tg of 64° C., Mn of 4,700, and Mw of 36,200.

<Production of Polyester Resin PD>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 67.8 parts ofterephthalic acid, 15.2 parts of ethylene glycol, and 17.0 parts ofneopentyl glycol, and the mixture was heated at 260° C. for 4 hours toperform an esterification reaction. Then, 2.41 parts of an ethyleneglycol solution containing 1.0 mass % of antimony trioxide as a catalystwas added to the reaction mixture and the temperature of the system waselevated to 280° C. and the pressure of the system was graduallydecreased to 13 Pa after 1.5 hours. Under the conditions, thepolycondensation reaction was further continued. After 2 hours, thepressure of the system was made normal with nitrogen gas and thetemperature of the system was lowered. When the temperature reached 270°C., 7.7 parts of trimellitic acid and 3.4 parts of isophthalic acid wereadded to the reaction mixture, which was then stirred at 250° C. for 1hour to perform polymerization reaction. Thereafter, the reactionmixture was sufficiently cooled to room temperature and then the polymerwas taken out to obtain a polyester resin PD. The polyester resin PDcontained no THF-insoluble matter and had an acid value of 83.6 mgKOH/g,a hydroxyl value of 0.7 mgKOH/g, Tg of 63.2° C., Mn of 1,850, and Mw of5,900.

<Production of Polyester Resin PE>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 70.0 parts of 2 molepropylene oxide adduct of bisphenol A, 20.0 parts of terephthalic acid,10.0 parts of 5-sulfoisophthalic acid, and 2.0 parts of potassiumtitanyl oxalate as a condensation catalyst and the mixture was allowedto react at 230° C. for 10 hours under nitrogen stream with distillingoff generated water. Then, the reaction mixture was allowed to reactunder reduced pressure of 5 to 20 mmHg. The polymer was taken out whenthe acid value reached 35 mgKOH/g to obtain a polyester resin PE. Thepolyester resin PE had an acid value of 35.0 mgKOH/g, a hydroxyl valueof 35.0 mgKOH/g, Tg of 65.2° C., Mn of 4,300, and Mw of 28,000.

<Production of Polyester Resin PF>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 56.0 parts of 2 molepropylene oxide adduct of bisphenol A, 10.0 parts of1-amino-2-hydroxy-4-naphthalenesulfonic acid, 25.0 parts of terephthalicacid, 5.0 parts of trimellitic anhydride, and 2 parts of potassiumtitanyl oxalate as condensation catalyst and the mixture was allowed toreact at 230° C. for 10 hours under nitrogen stream with distilling offgenerated water. Then, the reaction mixture was allowed to react underreduced pressure of 5 to 20 mmHg. The polymer was taken out when theacid value reached 48 mgKOH/g to obtain a polyester resin PF. Thepolyester resin PF contained 6.0 mass % of a THF-insoluble matter andhad an acid value of 47.4 mgKOH/g, a hydroxyl value of 27.0 mgKOH/g, Tgof 65° C., Mn of 4,600, and Mw of 22,700.

<<Production of Sulfonic Ester Group-Containing Resin>>

Synthesis of resins for toner (toner resins) S1 to S9 was performed bythe following methods.

<Production of Toner Resin S1>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of xyleneand 70 parts of the polyester resin PA and the mixture was stirred at50° C. under a nitrogen stream.

Then, the following monomers were mixed to prepare a monomer mixedliquid. Methyl 2-acrylamidebenzenesulfonate 7.5 parts Styrene 18.0 partsn-Butyl acrylate 4.5 parts

The monomer mixed liquid was further mixed with 1.8 parts of t-butylperoxyisopropylmonocarbonate (Perbutyl I, manufactured by NOFCORPORATION.) as a polymerization initiator and the mixture was droppedinto the above-mentioned reaction vessel. The temperature of theresultant mixture was elevated to 120 to 125° C. The mixture was stirredunder reflux conditions for 4 hours and then cooled to room temperature.Thereafter, the polymerized solution was dropwise added to 600 parts ofhexane to perform reprecipitation for purification and the obtainedpolymer was washed with 200 parts of hexane twice. After filtration, theresidue was dried at 40° C. under reduced pressure to obtain resinpowder having a slightly yellow color. This was named toner resin S1.

Analysis of structure indicated that the structure including the arylgroup having a sulfonic ester group as a substituent and a linking groupcontained in the toner resin S1 was as follows. Further, results ofmeasurement of sulfur content by combustion ion chromatography confirmedthat the content of sulfonic ester group was 0.31 mmol/g.

<Production of Toner Resin S2>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 200 parts oftetrahydrofuran and the mixture was stirred under a nitrogen stream.

Then, the following monomers were mixed to prepare a monomer mixedliquid. Methyl 2-acrylamidebenzenesulfonate 13.0 parts Styrene 66.0parts Acrylic acid 1.0 parts

20 parts of the polyester resin PA was dissolved in the monomer mixedliquid and further 3.0 parts of 2,2′-azobis(2,4-dimethylvaleronitrile)was mixed. The resultant was dropped to the above-mentioned reactionvessel while being stirred and retained for 10 hours. Thereafter, themixture was evaporated to distill off the solvent and the residue wasdried at 50° C. under reduced pressure. The obtained solids werepulverized to obtain a toner resin S2.

Analysis of the structure of the resin for toner S2 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the resin for toner S2 wasas follows.

<Production of Resin for Toner S3>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of thehybrid resin HA and 133 parts of 4-metoxyaniline-2-sulfonic acid andfurther 380 parts of pyridine. After the mixture was stirred, 406 partsof triphenyl phosphite was added and the mixture was heated at 120° C.for 6 hours. After completion of the reaction, the product wasreprecipitated in 500 parts of ethanol and recovered. The obtainedpolymer was washed twice with 200 parts of 1 mol/l hydrochloric acid andthen washed twice with 200 parts of water. The residue was dried underreduced pressure. Results of IR measurement indicated that the peak at1,695 cm⁻¹ attributable to a carboxylic acid decreased as compared tothe measurement in the case of the hybrid resin HA and a new peakattributable to an amide bond appeared at 1,658 cm⁻¹. In addition,results of ¹H-NMR indicated that the peak attributable to the methoxygroup of 4-methoxyaniline-2-sulfonic acid shifted, confirming that theobtained polymer contained a sulfonic acid group. Further, results ofmeasurement of sulfur content by combustion ion chromatography confirmedthat the content of sulfonic acid group was 0.62 mmol/g.

Further, in a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 400 parts oftrimethyl orthoformate and heated at 80° C. To this was added 100 partsof the obtained polymer in 5 minutes, and then the mixture was stirredfor 15 hours. Thereafter, the reaction mixture was dropwise added to9,000 parts of hexane while being stirred. After standing for a while, aresin was allowed to deposit and precipitate. The supernatant wasremoved by decantation, and 500 parts of chloroform was added to theresidue to dissolve it. The resultant was dropwise added to 7,500 partsof hexane while being stirred and allowed to deposit and precipitate.After removing the supernatant by decantation, the residue was driedunder reduced pressure. The resultant was washed with 300 parts ofmethanol and then with 300 parts of water. The residue was dried underreduced pressure to obtain a toner resin S3.

Analysis of the structure of the toner resin S3 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S3 was asfollows.

Note that while the content of sulfonic ester group was 0.52 mmol/g,this was obtained by measuring an acid value attributable to thesulfonic acid group of the toner resin S3 and obtaining a difference inacid value from the acid value attributable to sulfonic acid group ofthe compound before the esterification.

<Production of Toner Resin S4>

A toner resin S4 was obtained in the same manner as in the productionexample of toner resin S3 except that 800 parts of triethyl orthoformatewas used instead of 400 parts of trimethyl orthoformate.

Analysis of the structure of the toner resin S4 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S4 was asfollows.

<Production of Toner Resin S5>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of thehybrid resin HA and 147 parts of 2-amino-1-naphthalenesulfonic acid andfurther 380 parts of pyridine. After the mixture was stirred, 406 partsof triphenyl phosphite was added and the mixture was heated at 120° C.for 6 hours. After completion of the reaction, the product wasreprecipitated in 500 parts of ethanol and recovered. The obtainedpolymer was washed twice with 200 parts of 1 mol/l hydrochloric acid andthen washed twice with 200 parts of water. The residue was dried underreduced pressure. Results of IR measurement indicated that the peak at1,695 cm⁻¹ attributable to a carboxylic acid decreased and a new peakattributable to an amide bond appeared at 1,658 cm⁻¹. In addition,results of ¹H-NMR indicated that the peak attributable to the naphthylgroup of 2-amino-1-naphthalenesulfonic acid shifted, confirming that theobtained polymer contained a sulfonic acid unit.

Further, in a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 100 parts of theobtained polymer, and 3,500 parts of chloroform and 800 parts ofmethanol were added thereto to dissolve the polymer, followed by coolingthe solution to 0° C. To this was added 75 parts of 2 mol/ltrimethylsilyldiazomethane-hexane solution (manufactured by AldrichCorporation) and the mixture was stirred for 4 hours. Thereafter, thesolvent was removed by distillation.

2,500 parts of toluene and 1,000 parts of methyl ethyl ketone were addedto the residue to redissolve the polymer and the solvent was removed bydistillation. The operation of redissolution/distillation was repeatedthree times and the residue was dried at 50° C. under reduced pressure.The obtained solids were pulverized to obtain a toner resin S5.

Analysis of the structure of the toner resin S5 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S5 was asfollows:

<Production of Toner Resin S6>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of thepolyester resin PC and 38 parts of 4-aminobenzenesulfonic acid andfurther 380 parts of pyridine. After the mixture was stirred, 135 partsof triphenyl phosphite was added and the mixture was heated at 120° C.for 6 hours. After completion of the reaction, the product wasreprecipitated in 500 parts of ethanol and recovered. The obtainedpolymer was washed twice with 200 parts of 1 mol/l hydrochloric acid andthen washed twice with 200 parts of water. The residue was dried underreduced pressure. Results of IR measurement indicated that the peak at1,695 cm⁻¹ attributable to a carboxylic acid decreased and a new peakattributable to an amide bond appeared at 1,658 cm⁻¹. In addition,results of ¹H-NMR indicated that the peak attributable to the aromaticring of 4-aminobenzenesulfonic acid shifted, confirming that theobtained polymer contained a sulfonic acid unit.

Further, in a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 800 parts oftrimethyl orthoformate and heated at 80° C. To this was added 100 partsof the obtained polymer in 5 minutes, and then the mixture was stirredfor 15 hours. Thereafter, the reaction mixture was dropwise added to9,000 parts of hexane while being stirred. After standing for a while, aresin was allowed to deposit and precipitate. The supernatant wasremoved by decantation, and 500 parts of chloroform was added to theresidue to dissolve it. The resultant was dropped in 7,500 parts ofhexane while being stirred and allowed to deposit and precipitate. Afterremoving the supernatant by decantation, the residue was dried underreduced pressure. The resultant was washed with 300 parts of methanoland then with 300 parts of water. The residue was dried under reducedpressure to obtain a toner resin S6.

Analysis of the structure of the toner resin S6 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S6 was asfollows:

<Production of Toner Resin S7>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 100 parts of thepolyester resin PD and 140 parts of 4-aminotoluene-3-sulfonic acid andfurther 380 parts of pyridine. After the mixture was stirred, 463 partsof triphenyl phosphite was added and the mixture was heated at 120° C.for 6 hours. After completion of the reaction, the product wasreprecipitated in 500 parts of ethanol and recovered. The obtainedpolymer was washed twice with 200 parts of 1 mol/l hydrochloric acid andthen washed twice with 200 parts of water. The residue was dried underreduced pressure. Results of IR measurement indicated that the peak at1,695 cm⁻¹ attributable to a carboxylic acid decreased and a new peakattributable to an amide bond appeared at 1,658 cm⁻¹. In addition,results of ¹H-NMR indicated that the peak attributable to the methylgroup of 4-aminotoluene-3-sulfonic acid shifted, confirming that theobtained polymer contained a sulfonic acid unit.

Further, in a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 100 parts of theobtained polymer, and 3,500 parts of chloroform and 800 parts ofmethanol were added thereto to dissolve the polymer, followed by coolingthe solution to 0° C. To this was added 75 parts of 2 mol/ltrimethylsilyldiazomethane-hexane solution (manufactured by AldrichCorporation) and the mixture was stirred for 4 hours. Thereafter, thesolvent was removed by distillation.

2,500 parts of toluene and 1,000 parts of methyl ethyl ketone were addedto the residue to redissolve the polymer and the solvent was removed bydistillation. The operation of redissolution/distillation was repeatedthree times and the residue was dried at 50° C. under reduced pressure.The obtained solids were pulverized to obtain a toner resin S7.

Analysis of the structure of the toner resin S7 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S7 was asfollows:

<Production of Toner Resin S8>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 400 parts oftrimethyl orthoformate and heated at 80° C. To this was added 100 partsof the polyester resin PE in 5 minutes, and then the mixture was stirredfor 15 hours. Thereafter, the reaction mixture was dropwise added to9,000 parts of hexane while being stirred. After standing for a while, aresin was allowed to deposit and precipitate. The supernatant wasremoved by decantation, and 500 parts of chloroform was added to theresidue to dissolve it. The resultant was dropwise added to 7,500 partsof hexane while being stirred and allowed to deposit and precipitate.After removing the supernatant by decantation, the residue was driedunder reduced pressure. The resultant was washed with 300 parts ofmethanol and then with 300 parts of water. The residue was dried underreduced pressure to obtain a toner resin S8.

Analysis of the structure of the toner resin S8 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S8 was asfollows.

<Production of Toner Resin S9>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe was charged 400 parts oftrimethyl orthoformate and heated at 80° C. To this was added 100 partsof the polyester resin PF in 5 minutes, and then the mixture was stirredfor 15 hours. Thereafter, the reaction mixture was dropwise added to9,000 parts of hexane while being stirred. After standing for a while, aresin was allowed to deposit and precipitate. The supernatant wasremoved by decantation, and 500 parts of chloroform was added to theresidue to dissolve it. The resultant was dropwise added to 7,500 partsof hexane while being stirred and allowed to deposit and precipitate.After removing the supernatant by decantation, the residue was driedunder reduced pressure. The resultant was washed with 300 parts ofmethanol and then with 300 parts of water. The residue was dried underreduced pressure to obtain a toner resin S9.

Analysis of the structure of the toner resin S9 indicated that thestructure including the aryl group having a sulfonic ester group as asubstituent and a linking group contained in the toner resin S9 was asfollows.

<Production of St/2EHA/AMPS Copolymer (for Comparative Example)>

In a reaction vessel equipped with a condenser, a stirrer, athermometer, and a nitrogen inlet pipe were charged 67 parts ofmethanol, 50 parts of toluene, and 83 parts of methyl ethyl ketone andthe mixture was refluxed under a nitrogen stream.

Then, the following monomers were mixed to the resultant to prepare amonomer mixed liquid. 2-Acrylamide-2-methylpropanesulfonic acid 6.0parts Styrene 81.0 parts 2-Ethylhexyl acrylate 13.0 parts

To this mixed liquid was added 5.0 parts ofdimethyl-2,2′-azobis(2-methylpropionate) as a polymerization initiator.The resultant mixture was dropped in the above-mentioned reaction vesselwhile being stirred and retained for 10 hours. Thereafter, the solventwas removed by distillation and the residue was dried at 50° C. underreduced pressure. The obtained solids were pulverized to obtain anSt/2EHA/AMPS copolymer. This resin had an acid value of 28.0 mgKOH/g, ahydroxyl value of 0 mgKOH/g, Tg of 63.1° C., Mn of 10,700, and Mw of24,000.

Table 1 shows components and contents of the polyester unit and contentsof sulfonic ester group and total sulfonic functional group (sum ofsulfonic acid group and sulfonic ester group) relating to the tonerresins S1 to S9 thus prepared and Table 2 shows results of acid values,molecular weights, and Tg measured by the above-mentioned methods. TABLE1 Polyester unit components (molar ratio) Polyhydric Sulfonic esterTotal sulfonic Toner Type of alcohol Polycarboxylic Polyester unit groupcontent functional group resin resin component acid component content(mass %) (mmol/g) content (mmol/g) S1 Hybrid BPA-PO 100.0 Dimethyl 700.31 0.31 resin terephthalate 91.2 S2 Hybrid BPA-PO 100.0 Dimethyl 200.54 0.54 resin terephthalate 91.2 S3 Hybrid Propylene Terephthalicacid/Adipic 60 0.52 0.62 resin glycol 100.0 acid/Maleic anhydride103.8/9.7/23.5 S4 Hybrid Propylene Terephthalic acid/Adipic 60 0.55 0.62resin glycol 100.0 acid/Maleic anhydride 103.8/9.7/23.5 S5 HybridPropylene Terephthalic acid/Adipic 60 0.39 0.41 resin glycol 100.0acid/Maleic anhydride 103.8/9.7/23.5 S6 Polyester BPA-PO 100.0Terephthalic acid/ 100 0.18 0.21 resin Trimellitic anhydride 74.0/11.7S7 Polyester Neopentyl glycol/ Terephthalic acid/ 100 1.05 1.10 resinEthylene glycol Isophthalic acid/ 40.0/60.0 Trimellitic acid100.0/5.0/9.0 S8 Polyester BPA-PO 100.0 Terephthalic acid 100 0.37 0.41resin (/5-sulfoisophthalic acid) 59.2(/20.1) S9 Polyester BPA-PO(/AHNS)Terephthalic acid/ 100 0.36 0.41 resin 79.8 Trimellitic anhydride(/20.4) 74.0/11.7BPA-PO: 2-mole propylene oxide adduct of bisphenol AAHNS: 1-amino-2-hydroxy-4-naphthalenesulfonic acid

TABLE 2 Toner Acid value Molecular weight Tg resin (mgKOH/g) Mw Mw/Mn (°C.) S1 2.2 12,000 5.5 55.1 S2 7.5 7,300 2.8 67.2 S3 12.5 8,000 2.8 54.5S4 9.2 8,050 2.8 54.0 S5 2.2 7,900 2.8 53.8 S6 2.3 36,500 7.8 63.8 S77.5 6,100 3.4 61.4 S8 5.2 28,000 6.5 65.2 S9 5.9 22,700 4.9 62.7

<<Production of Toner>>

Toners 1 to 11 were produced by the following methods.

<Production of Toner 1>

Preparation of Pigment Dispersed Paste: Styrene monomer 80 parts Cuphthalocyanine (Pigment Blue 15:3) 13 parts

The above-mentioned materials were well premixed in a vessel and theresultant was dispersed with a bead mill for about 4 hours while beingkept at 20° C. or lower to prepare a pigment-dispersed paste.

Preparation of Toner Particles:

To 1,150 parts of deionized water was added 390 parts of a 0.1 mol/lNa₃PO₄ aqueous solution and the resultant mixture was heated to 60° C.Then the mixture was stirred using a CLEARMIX (manufactured byMtechnique Corporation) at 11,000 rpm. To the resultant was graduallyadded 58 parts of a 1.0 mol/l CaCl₂ aqueous solution to obtain adispersion medium containing Ca₃(PO₄)₂ The above-mentioned pigmentdispersed paste 46.5 parts Styrene monomer 42.0 parts n-Butyl acrylate18.0 parts Ester wax (Main component C₁₉H₃₉COOC₂₀H₄₁, 13.0 parts meltingpoint 68.6° C.) Saturated polyester resin (Terephthalic acid- 5.0 partspropylene oxide modified bisphenol A copolymer, acid value 15 mgKOH/g,Mw 18,000) Toner resin S1 1.5 parts

These were heated to 60° C., dissolved and dispersed to form a monomermixture. 3.0 parts of 2,2′-azobis(2,4-dimethylvaleronitrile) as apolymerization initiator was added to the monomer mixture fordissolution while the monomer mixture being kept at 60° C., to therebyprepare a monomer composition.

The monomer composition was charged to the above-mentioned dispersionmedium. At 60° C. in a nitrogen atmosphere, the mixture was stirredusing a CLEARMIX at 10,000 rpm for 20 minutes and granulated.Thereafter, the resultant particles were allowed to react at 60° C. for5 hours while being stirred using a paddle stirring vane, followed bystirring at 80° C. for 5 hours to complete the polymerization. After theparticles were cooled to room temperature, hydrochloric acid was addedthereto to dissolve Ca₃(PO₄)₂, and the powders were filtered, washed anddried and further classified to obtain toner particles.

Preparation of Toners:

To 100 parts of the obtained toner particles was mixed and externallyadded 1 part of hydrophobic silica fine powder having a number averageprimary particle diameter of 9 nm and a BET specific surface area of 180m²/g, which was obtained by treating the surface thereof withhexamethyldisilazane and subsequently with silicone oil, by using aHenschel mixer (manufactured by Mitsui Miike Chemical EngineeringMachine Co., Ltd.), to thereby obtain a toner 1.

<Production of Toner 2>

A toner 2 was obtained in the same manner as in the production exampleof toner 1 except that the toner resin S2 was used instead of the tonerresin S1.

<Production of Toner 3>

Preparation of Pigment Dispersed Paste: Styrene monomer 80 parts Carbonblack (Printex 35, manufactured by Degussa AG) 13 parts

The above-mentioned materials were well premixed in a vessel and theresultant was dispersed with a bead mill for about 4 hours while beingkept at 20° C. or lower to prepare a pigment-dispersed paste.

Preparation of Toner Particles:

To 1,200 parts of deionized water was added 350 parts of a 0.1 mol/lNa₃PO₄ aqueous solution and the resultant mixture was heated to 60° C.Then the mixture was stirred using a TK-type Homomixer (manufactured byPRIMIX Corporation) at 11,000 rpm. To the resultant was gradually added52 parts of a 1.0 mol/l CaCl₂ aqueous solution to obtain a dispersionmedium containing Ca₃(PO₄)₂. The above Pigment dispersed paste 46.5parts Styrene monomer 38.0 parts n-Butyl acrylate 22.0 parts Hydrocarbonwax (Mw 1850, Mw/Mn 1.27, melting point 10.0 parts 78.6° C.) Toner resinS3 3.0 parts

These were heated to 60° C., dissolved and dispersed to form a monomermixture. 5 parts of 2,2′-azobis(2,4-dimethylvaleronitrile) as apolymerization initiator was added to the monomer mixture fordissolution while the monomer mixture being kept at 60° C., to therebyprepare a monomer composition.

The monomer composition was charged to the above-mentioned dispersionmedium. At 60° C. in a nitrogen atmosphere, the mixture was stirredusing a CLEARMIX at 10,000 rpm for 20 minutes and granulated.Thereafter, the resultant particles were allowed to react at 60° C. for5 hours while being stirred using a paddle stirring vane, followed bystirring at 80° C. for 5 hours to complete the polymerization. After theparticles were cooled to room temperature, hydrochloric acid was addedthereto to dissolve Ca₃(PO₄)₂, and the powders were filtered, washed anddried and further classified to obtain toner particles. Then, thehydrophobic silica fine powder was externally added in the same manneras in the production example of toner 1 to obtain a toner 3.

<Production of Toner 4>

A toner 4 was obtained in the same manner as in the production exampleof toner 3 except that 10.0 parts of the toner resin S4 was used insteadof 3.0 parts of the toner resin S3.

<Production of Toner 5>

Preparation of Toner Composition Mixed Liquid:—

Propylene oxide adduct of bisphenol A/ethylene oxide adduct of bisphenolA/terephthalic acid copolymer polyester resin 100.0 parts (Tg 62° C.,softening point 102° C., Mw 21,000) 5.0 parts Cu phthalocyanine (PigmentBlue 15:3) Hydrocarbon wax (Mw 1,850, Mw/Mn 1.27, melting point 8.0parts 78.6° C.) Toner resin S5 5.0 parts Ethyl acetate 100.0 parts

The above-mentioned materials were well premixed in a vessel and theresultant was dispersed with a bead mill while being kept at 20° C. orlower for about 4 hours to prepare a toner composition mixed liquid.

Preparation of Toner Particles:

To 240 parts of deionized water was charged 78 parts of a 0.1 mol/lNa₃PO₄ aqueous solution and the resultant mixture was heated to 60° C.Then, the mixture was stirred using A TK-type Homomixer (manufactured byPrimix Corporation) at 11,000 rpm. To the resultant was gradually added12 parts of a 1.0 mol/l CaCl₂ aqueous solution to obtain a dispersionmedium containing Ca₃(PO₄)₂. Further, 1.0 part of carboxymethylcellulose(trade name: CELLOGEN BS-H, manufactured by Daiichi Kogyo Seiyaku Co.,Ltd.) was added to the dispersion medium and the mixture was stirred for10 minutes.

The dispersed medium prepared in the vessel of the above-mentionedhomomixer was adjusted to 30° C. and while it was being stirred, 180parts of the toner composition mixed liquid adjusted to 30° C. wascharged, followed by stirring for 1 minute. Then, the stirring wasstopped to obtain a toner composition-dispersed suspension. While theobtained toner composition-dispersed suspension was stirred, the gasphase on the surface of the suspension was forcibly renewed using alocal exhaust apparatus at 40° C. constant, and the suspension wasretained as it was for 17 hours to remove the solvent. After the residuewas cooled to room temperature, hydrochloric acid was added thereto todissolve Ca₃(PO₄)₂, and the residue was filtered, washed, dried, andfurther classified to obtain toner particles. Then, in the same manneras the production example of toner 1, the hydrophobic silica fine powderwas externally added to the toner particles to obtain a toner 5.

<Production of Toner 6>

Toner 6 was obtained in the same manner as in the production example oftoner 5 except that 10.0 parts of the toner resin S6 was used instead of5.0 parts of the toner resin S5.

<Production of Toner 7>

Production of resin dispersion: Styrene 370 parts n-Butyl acrylate 30parts Acrylic acid 6 parts Dodecanethiol 24 parts Carbon tetrabromide 4parts

A mixed liquid of the above composition was dispersed and emulsified ina solution prepared by dissolving 6 parts of a nonionic surfactant(Nonipol 400, manufactured by Sanyo Chemical Industries, Ltd.) and 10parts of an anionic surfactant (Neogen SC, manufactured by Daiichi KogyoSeiyaku Co., Ltd.) in 550 parts of deionized water in a flask, and whilethe resultant was mixed slowly for 10 minutes, 50 parts of deionizedwater having dissolved therein 4 parts of ammonium persulfate wascharged in the flask and nitrogen purge was performed. Thereafter, theflask was heated in an oil bath until the contents reached 70° C. whilethe contents of the flask were stirred and emulsion polymerization wascontinued in this state for 5 hours. As a result, there was obtained aresin dispersion having a center diameter of 155 nm, a glass transitiontemperature of 59° C., and a Mw of 12,000.

Production of toner resin S3 dispersion:

40 parts of the toner resin S3 was added to 360 parts of deionized waterand the mixture was heated to 90° C. Then the mixture was adjusted topH=7 with 5% ammonia water, and the mixture was stirred using a UltraTurrax T-50 (manufactured by IKA) at 8,000 rpm while 0.8 part of a 10%aqueous solution of dodecylbenzenesulfonic acid was added, to therebyprepare a dispersion of toner resin S3 having a center diameter of 200nm.

Preparation of Pigment Dispersion:

The following composition was mixed and dissolved, and dispersed with ahomogenizer (IKA Ultra Turrax) and by ultrasonic irradiation, to therebyobtain a blue pigment dispersion having a center particle diameter of150 nm. Cyan pigment C.I. Pigment Blue 15:3 50 parts Anionic surfactant(Neogen SC, manufactured by 5 parts Daiichi Kogyo Seiyaku Co., Ltd.)Deionized water 200 parts

Preparation of Release Agent Dispersion:

The following composition was mixed and heated at 97° C., and thendispersed using a Ultra Turrax T-50 manufactured by IKA. Thereafter, thedispersion was subjected to dispersion treatment using a Gaulinhomogenizer (manufactured by Meiwa Fosis Co., Ltd.) and treated 20 timesunder the conditions of 105° C. and 550 kg/cm², to thereby obtain arelease agent dispersion having a center diameter of 190 nm. Hydrocarbonwax (Mw 1,850, Mw/Mn 1.27, melting point 100 parts 78.6° C.) Anionicsurfactant (Neogen SC, manufactured by 5 parts Daiichi Kogyo SeiyakuCo., Ltd.) Deionized water 300 parts Production of toner particles: Theabove-mentioned resin dispersion 200 parts The above-mentioned pigmentdispersion 30 parts The above-mentioned release agent dispersion 30parts Sanisol B50 (manufactured by Kao, Ltd.) 1.5 parts

These were mixed and dispersed in a round type stainless steel flaskusing a Ultra Turrax T-50, and then the dispersion was heated to 48° C.in an oil bath for heating while the contents of the flask were stirred.After the resultant was retained at 48° C. for 30 minutes, observationof the mixture using an optical microscope confirmed the formation ofagglomerated particles of about 5 μm. To this was gently added 60 partsof the toner resin S3 dispersion and the temperature of the oil bath forheating was elevated to 50° C. and the resultant mixture was retained atthis temperature for 1 hour. Observation of the product on an opticalmicroscope confirmed the formation of agglomerated particles of about5.6 μm. Thereafter, 3 parts of Neogen SC was added to the resultant andthen the stainless steel flask was sealed. The product was heated to105° C. while being continuously stirred using a magnetic seal andretained for 3 hours. After cooling, the resultant was filtered,sufficiently washed with deionized water, and dried, and furtherclassified to obtain toner particles. Then, hydrophobic silica finepowder was externally added to the obtained toner particles in the samemanner as in the production example of toner 1 to obtain a toner 7.

<Production of Toner 8>

A toner 8 was obtained in the same manner as in the production exampleof toner 7 except that the toner resin S9 was used instead of the tonerresin S3.

<Production of Toner 9>

A toner 9 was obtained in the same manner as in the production exampleof toner 1 except that the polyester PE was used instead of the tonerresin S1.

<Production of Toner 10>

A toner 10 was obtained in the same manner as in the production exampleof toner 1 except that the St/2EHA/AMPS copolymer was used instead ofthe toner resin S1.

<Production of Toner 11>

A toner 11 was obtained in the same manner as in the production exampleof toner 1 except that 1.0 part of a zinc complex of 3,5-di-tert-butylsalicylic acid was used instead of 1.5 parts of the toner resin S1.

The above-mentioned toners 1 to 11 were measured for weight averageparticle diameter (D4) and circularity by the above-mentioned methods,and further DSC measurement was performed. Table 3 shows the results.TABLE 3 DSC Measurement Charge control compound Maximum heat GlassAddition Weight average absorption peak transition amount particlediameter Average temperature temperature Kind (mass part) (μm)circularity (° C.) (° C.) Example Toner 1 Toner resin S1 1.5 6.24 0.98368.8 58.2 Toner 2 Toner resin S2 1.5 6.31 0.980 68.8 58.0 Toner 3 Tonerresin S3 3.0 6.18 0.981 73.8 57.3 Toner 4 Toner resin S4 10.0 5.83 0.98673.8 57.9 Toner 5 Toner resin S5 5.0 6.55 0.980 74.1 59.8 Toner 6 Tonerresin S6 10.0 6.65 0.978 74.1 60.6 Toner 7 Toner resin S3 7.7 6.04 0.97073.6 59.5 Toner 8 Toner resin S9 7.7 6.04 0.969 73.4 60.4 ComparativeToner 9 Polyester resin PE 1.5 7.42 0.978 68.8 58.4 Example Toner 10St/2EHA/AMPS 1.5 7.26 0.976 68.8 58.5 Copolymer Toner 11 Zinc complex of1.0 6.22 0.983 68.8 58.3 di-t-butyl salicylic acid

As shown in Table 3, toners 9 and 10 each had a slightly greater weightaverage particle diameter than toner 1. Toners 9 and 10 contained bothcoarse powder and fine powder in large amounts and had an extremelybroad particle diameter distribution, and many agglomerates wereobserved. The yield of each of the toners 9 and 10 upon classificationwas about 50% as compared with toner 1.

Further, toners 1 to 11 were evaluated for printing out as follows.Table 4 shows the results.

—Printing Test Method

By using a commercially available full color laser beam printer(LBP-5500, manufactured by Canon, Inc.), 200 g of a toner was filled ina developing device and continuous printing test of 10,000 sheets wasperformed in a normal temperature and normal humidity environment (23.5°C., 60% RH). Further, the printer was moved to an environment under hightemperature and high humidity conditions (30° C., 80% RH) and left tostand for 24 hours. Then, continuous printing test of 5,000 sheets wasperformed. During the printing tests, fifth sheet was defined initial,10,000-th sheet was defined as after endurance running, and 15,000-thsheet was defined after severe endurance running and charge amount oftoner on toner carrier, image density, and fog density at each time weremeasured. In these tests, the printing speed was set to 17 sheets/minuteof A4 wide (A4 plain paper of 75 g/m²), and the print ratio of eachcolor to paper area was set to 2%.

The fog density on images was measured using a reflection densitometer(Reflectometer Model TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.)and evaluation of fog was performed as follows. Assuming the worst whitebackground reflection density after printing out was Ds, and averagereflection density on paper before printing out was Dr, Ds−Dr wasdefined as a fog quantity. When this value is 1.0% or less, suppressionof fog is an extremely good level while when this value is 1.5% or less,the image is an image in which fog is substantially well-suppressed.TABLE 4 Charge quantity (μC/g) Image density Fog density After AfterAfter After severe After severe After severe endurance enduranceendurrance endurance endurance endurance Initial running running Initialrunning running Initial running running Example Toner 1 −40.3 −39.9−38.2 1.51 1.50 1.48 0.6 0.6 0.7 Toner 2 −38.2 −38.6 −37.6 1.50 1.501.49 0.6 0.6 0.7 Toner 3 −44.2 −43.9 −40.2 1.48 1.48 1.47 0.5 0.5 0.6Toner 4 −48.5 −48.1 −45.1 1.47 1.48 1.48 0.4 0.4 0.5 Toner 5 −39.8 −39.4−37.0 1.49 1.48 1.46 0.7 0.8 0.8 Toner 6 −35.8 −38.7 −36.5 1.44 1.471.47 0.9 0.8 0.8 Toner 7 −41.5 −40.6 −39.9 1.46 1.46 1.46 0.8 0.8 0.8Toner 8 −38.9 −42.1 −38.7 1.45 1.47 1.45 0.9 0.7 0.9 Comparative Toner 9−35.7 −31.0 −19.8 1.45 1.40 1.18 0.9 1.2 2.1 Example Toner 10 −18.4−33.5 −18.7 1.13 1.33 1.14 1.6 1.0 1.9 Toner 11 −39.3 −38.4 −29.4 1.501.48 1.39 0.8 0.9 1.6

Table 4 indicates that the toners 1 to 8 of the examples of the presentinvention each had good charging properties from the initial stage inprinting out tests and it was confirmed that the good charging propertycould be maintained when 10,000 sheets were printed. Further, at thetime of printing of 5,000 sheets under high temperature and highhumidity conditions subsequently performed, a high charging property wasmaintained. As a result, both the image density and fog density were atgood values and stable through duration.

On the other hand, although the toner 9 of the comparative exampleshowed a relatively high value of initial charging quantity, this valuewas decreased slightly when 10,000 sheets were printed. Further, it wasconfirmed that the value was greatly decreased when 5,000 sheets wereprinted under high temperature and high humidity conditions. The imagedensity was decreased as the charging quantity was decreased andfinally, the image density was greatly decreased and in addition, thefog density showed a high value. Further, the toner 10 showed a lowinitial charging quantity, resulting in a poor charge rising property.In this toner, although the charging quantity increased as durationproceeds, it was decreased again under high temperature and highhumidity conditions. As a result, satisfactory image density could notbe obtained throughout duration. Further, the fog density scored a highvalue. The toner 11 showed a high charging quantity at the initial stageand also after printing of 10,000 sheets, and also showed good imagedensity and good fog density. However, under high temperature and highhumidity conditions, a slight decrease in a charging quantity wasconfirmed and also a decrease in image density was observed. Inaddition, the fog density was significantly increased.

<Production of Toner 12>

A mixture of the following materials was mixed well with a Henschelmixer (FM-57 Model, manufactured by Mitsui Miike Chemical EngineeringMachine Co., Ltd.) and kneaded with a twin-screw kneader (PCM-30 Model,manufactured by Ikegai Corporation) set at a temperature of 130° C.Styrene-butyl acrylate-divinylbenzene copolymer 85.0 parts (Tg 58° C.,Mn 8,000, Mw 120,000) Toner resin S7 15.0 parts Magnetic iron oxide100.0 parts (average particle diameter 0.18 μm) Polymethine wax (Mw:1,850, Mw/Mn: 1.27, melting 5.0 parts point: 78.6° C.)

The obtained kneaded preparation was cooled and coarsely pulverized to 1mm or less using a hammer mill and then pulverized using a fine grindingmill by an air-jet method. The obtained pulverisates were classified toobtain toner particles. Further, hydrophobic silica fine powder wasexternally added to the toner particles in the same manner as in theproduction example of toner 1, to thereby obtain a toner 12.

The obtained toner 12 had a weight average particle diameter of 6.68 μm,an average circularity of 0.960, Tg of 56.9° C., and a heat absorptionmain peak at 74.0° C.

<Production of Toner 13>

A toner 13 was obtained in the same manner as in the production exampleof toner 12 except that 30 parts of the toner resin S8 was used insteadof 15 parts of the toner resin S7.

The obtained toner 13 had a weight average particle diameter (D4) of6.82 μm, an average circularity of 0.961, Tg 58.3° C., and a heatabsorption main peak at 74.3° C.

—Printing Test Method

By using a commercially available laser beam printer (LBP-930,manufactured by Canon, Inc.), 10,000 sheets were printed under normaltemperature and normal humidity conditions (23.5° C., 60% RH) andfurther 5,000 sheets were printed under high temperature and highhumidity conditions (30° C., 80% RH) while toner was supplied to theprinter if required.

As a result, toners 12 and 13 each had an image density of 1.47 to 1.50and the both were stable over a range of from the initial to afterduration of 10,000 sheets and good images were obtained. Further, theyboth maintained a toner charge quantity of −30.0 μC/g on the tonercarrier over a range of from initial to after duration of 10,000 sheets,thus showing good stability. Further, results of the measurement ofimage density and toner charging quantity in the case of printing underhigh temperature and high humidity conditions (30° C., 80% RH) indicatedthat they both maintained an image density of 1.45 or more and chargequantity of −25.0 μC/g or more. The above-mentioned results confirmedthat the toners 12 and 13 of the present invention were practicallyexcellent.

This application claims priority from Japanese Patent Application No.2005-327142 filed on Nov. 11, 2005, the contents of which isincorporated herein by reference.

1. A resin for toner comprising a resin component having both apolyester unit produced by polycondensation of a polyhydric alcoholcomponent and a polycarboxylic acid component, and an aryl group havinga sulfonic ester group as a substituent.
 2. A resin for toner accordingto claim 1, wherein the aryl group having a sulfonic ester group as asubstituent is a phenyl group having a sulfonic ester group as asubstituent or a naphthyl group having a sulfonic ester group as asubstituent.
 3. A resin for toner according to claim 1, wherein thesulfonic ester group has a structure represented by the followingformula:—SO₃R¹ where R¹ represents an alkyl group having 1 to 12 carbon atoms ora phenyl group.
 4. A resin for toner according to claim 1, wherein thearyl group having a sulfonic ester group as a substituent is bondedthrough any one of an amide bond, a urethane bond, and a urea bond.
 5. Aresin for toner according to claim 1, wherein the aryl group having asulfonic ester group as a substituent is bonded through an amide bond.6. A resin for toner according to claim 1, wherein the aryl group havinga sulfonic ester group as a substituent is bonded through an amide bondrepresented by the following formula:

where R¹⁰ to R¹³ independently represent a hydrogen atom, an alkyl grouphaving 1 to 4 carbon atoms, a hydroxyl group, or an alkoxyl group having1 to 4 carbon atoms, and R¹⁴ represents an alkyl group having 1 to 4carbon atoms.
 7. A resin for toner according to claim 1, wherein thetoner contains 0.1 to 0.9 mmol/g of the aryl group having a sulfonicester group as a substituent.
 8. A resin for toner according to claim 1,wherein the polyester unit is bonded to a vinyl polymer unit formed bypolymerization of a vinyl monomer component to form a hybrid resin.
 9. Aresin for toner according to claim 1, wherein the resin for toner has aweight average molecular weight (Mw) calculated by gel permeationchromatography within the range of 2,000 to 200,000.
 10. A resin fortoner according to claim 1, wherein the resin for toner has a ratio(Mw/Mn) of a weight average molecular weight (Mw) calculated by gelpermeation chromatography to a number average molecular weight (Mn)within the range of 1.0 to 6.0.
 11. A resin for toner according to claim1, wherein the resin for toner has a glass transition temperature withinthe range of 45 to 90° C. in a DSC curve measured by a differentialscanning calorimeter.
 12. A resin for toner according to claim 1,wherein the resin for toner has an acid value of 0.1 to 40.0 mgKOH/g.13. A toner comprising toner particles that contain at least a binderresin, a colorant, and a resin for toner according to claim
 1. 14. Atoner according to claim 13, wherein the resin for toner is contained inan amount of 0.1 to 20.0 parts by mass with respect to 100.0 parts bymass of the binder resin.
 15. A toner according to claim 13, wherein thetoner contains a wax and has a maximum heat absorption peak within therange of 45 to 130° C. in a DSC curve when the temperature of the toneris elevated as measured by a differential scanning calorimeter.
 16. Atoner according to claim 13, wherein the toner has a weight averageparticle diameter (D4) of 3.0 to 9.0 μm.
 17. A toner according to claim13, wherein the toner particles is one formed by a production methodthat involves a step of dispersing a composition that contains the resinfor toner in an aqueous medium.